Mobile Gas and Chemical Imaging Camera

Abstract

In one embodiment, an infrared (IR) imaging system for determining the concentration of a target substance in an object is disclosed. The imaging system may include an optical system that includes an optical focal plane array (FPA) unit. The optical system may have components that define at least two optical channels that are spatially and spectrally different from each other. Each of the at least two optical channels may be positioned to transmit IR radiation incident on the optical system toward the optical FPA. The system may include a processing unit that includes a processor that may be configured to acquire multispectral optical data representative of the target substance from the IR radiation received at the optical FPA. The optical system and the processing unit may be included together in a data acquisition and processing module that is configured to be worn or carried by a person.

Description

[0001] Incorporation by reference of any priority applications

[0002] Any and all applications for foreign or domestic priority claims identified in the application data sheet filed together with this application are incorporated herein by reference in accordance with 37 CFR 1.57

[0003] This application claims priority to U.S. Provisional Patent Application 62 / 411,480, filed October 21, 2016, entitled “MOBILE GAS AND CHEMICAL IMAGING CAMERA,” the contents of which are incorporated herein by reference in their entirety for all purposes

[0004] Statement regarding federally sponsored R&D

[0005] Some portions of the technology disclosed in this application were funded by the Advanced Research Projects Agency - Energy (ARPA - E) under Contract No. DE - AR0000541. The government may have certain rights in these portions of the technology Technical field

[0006] The present invention generally relates to systems and methods for gas cloud detection and, in particular, to systems and methods for detecting spectral signatures of chemical components in the infrared spectral region Background art

[0007] Spectral imaging systems and methods have applications in various fields. Spectral imaging systems and methods obtain spectral images of a scene in one or more regions of the electromagnetic spectrum to detect phenomena, identify material compositions, or characterize processes. The spectral image of a scene can be represented as a three - dimensional data cube, where two axes of the cube represent two spatial dimensions of the scene, and the third axis of the data cube represents the spectral information of the scene in different wavelength regions. Mathematical methods can be used to process the data cube to obtain information about the scene. Some existing spectral imaging systems generate the data cube by scanning the scene in the spatial domain (e.g., by moving a slit across the horizontal dimension of the scene) and / or by scanning the scene in the spectral domain (e.g., by scanning a wavelength dispersive element to obtain images of the scene in different spectral regions). Such a scanning scheme acquires only a portion of the complete data cube at a time. These portions of the complete data cube are stored and then processed to generate the complete data cube Summary of the invention

[0008] The systems, methods, and devices of the present disclosure each have several innovative aspects, none of which alone is responsible for the desired attributes disclosed herein.

[0009] In one embodiment, an infrared (IR) imaging system for determining the concentration of a target substance in an object (target species) is disclosed. The imaging system may include an optical system that includes an optical focal plane array (FPA) unit. The optical system may have components that define at least two optical channels thereof, the at least two optical channels being different from each other spatially and spectrally. Each of the at least two optical channels may be positioned to transmit IR radiation incident on the optical system toward the optical FPA. The system may include a processing unit that includes a processor that may be configured to acquire multispectral optical data representing the target substance from the IR radiation received at the optical FPA. The optical system and the processing unit may be included together in a data acquisition and processing module that is configured to be worn or carried by a person.

[0010] In another embodiment, an infrared (IR) imaging system for determining the concentration of a target substance in an object is disclosed. The imaging system may include an optical system that includes an optical focal plane array (FPA) unit. The optical system may have components that define at least two optical channels thereof, the at least two optical channels being different from each other spatially and spectrally. Each of the at least two optical channels may be positioned to transmit IR radiation incident on the optical system toward the optical FPA. The system may include a processing unit that includes a processor that may be configured to acquire multispectral optical data representing the target substance from the IR radiation received at the optical FPA. The data acquisition and processing module may have dimensions less than 8 inches x 6 inches x 6 inches.

[0011] In another embodiment, an infrared (IR) imaging system for determining the concentration of a target substance in an object is disclosed. The imaging system may include an optical system that includes an optical focal plane array (FPA) unit. The optical system may have components that define at least two optical channels thereof, the at least two optical channels being different from each other spatially and spectrally. Each of the at least two optical channels may be positioned to transmit IR radiation incident on the optical system toward the optical FPA. The system may include a processing unit that includes a processor that may be configured to acquire multispectral optical data representing the target substance from the IR radiation received at the optical FPA. The data acquisition and processing module may have a volume less than 300 cubic inches.

[0012] In yet another embodiment, a method of identifying a target substance or quantifying or characterizing a parameter of a target substance in an object is disclosed. The method can include wearing or carrying a data acquisition and processing module. The data acquisition and processing module can include an optical system and a processing unit in communication with the optical system, the optical system including an optical focal plane array (FPA) unit. The method can include capturing multi-spectral infrared (IR) image data at the FPA unit from at least two optical channels that are spatially and spectrally distinct from one another. The method can include collecting multi-spectral optical data representative of the target substance from the IR radiation received at the FPA.

[0013] In another embodiment, a system for monitoring the presence of one or more target gases at one or more installation sites is disclosed. The system can include a plurality of infrared (IR) imaging systems, each imaging system including a data acquisition and processing module. The data acquisition and processing module can be configured to capture in real time infrared images of one or more target gases. The data acquisition and processing module can be configured to associate each captured infrared image with a location where one or more target gases are present. The data acquisition and processing module can be configured to send image data associated with one or more target gases and location data associated with the location of one or more target gases to a central server.

[0014] In yet another embodiment, a method for monitoring the presence of one or more target gases at one or more installation sites is disclosed. The method can include receiving image data from a plurality of IR imaging systems located at the one or more installation sites and configured to be worn or carried by a person. Each IR imaging system can be configured to capture in real time infrared images of one or more target gases and associate each captured infrared image with a location where one or more target gases are present. The method can include processing the received image data to identify the installation sites at which one or more target gases are detected.

[0015] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions in the figures below may not be drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 An embodiment of an imaging system is shown that includes a common front objective having pupils that are spectrally separated and re-imaged onto an infrared FPA with a plurality of lenses.

[0017] Figure 2 An embodiment is shown having a separate front objective and an infrared sensing FPA array.

[0018] Figure 3A An embodiment is shown that employs a front objective lens array that is operatively matched to a re-imaging lens array. Figure 3B The diagram shows Figure 3A The embodiments correspond to a two-dimensional array of optical components.

[0019] Figure 4 is a diagram of an embodiment employing a field reference array (eg, a field stop that can be used as a calibration reference) and a corresponding relay lens array.

[0020] Figure 5A is a diagram of a 4 by 3 pupil array including circular optical filters (and IR blocking material between the optical filters) used to spectrally divide an optical wavefront imaged using an embodiment of the system.

[0021] Figure 5B is a diagram of a 4 by 3 pupil array including rectangular optical filters (and IR blocking material between the optical filters) used to spectrally divide an optical wavefront imaged using an embodiment of the system.

[0022] Figure 6A Depicted is a theoretical graph of the transmission characteristics of a bandpass filter combination used with embodiments of the system.

[0023] Figure 6B Depicted is a theoretical graph of the transmission characteristics of a spectrally multiplexed notch-pass filter combination used in an embodiment of the system.

[0024] Figure 6C A theoretical graph showing the transmission characteristics of a spectrally multiplexed longpass filter combination used in an embodiment of the system.

[0025] Figure 6D A theoretical graph showing the transmission characteristics of a spectrally multiplexed short-pass filter combination used in an embodiment of the system.

[0026] Figure 7 is a set of video frames illustrating the operability of an embodiment of a system for gas detection.

[0027] Figure 8A and 8B is a graph illustrating the results of dynamic calibration of an embodiment of the system (on an axis of wavelength in microns versus object temperature representing the effective optical intensity of the object in degrees Celsius).

[0028] Figure 9A and 9BA cross-sectional view of different embodiments of an imaging system is illustrated, the imaging system including an arrangement of a reference source and a mirror that can be used for dynamic calibration.

[0029] Figure 10A - 10C A plan view of different embodiments of an imaging system is illustrated, the imaging system including an arrangement of a mirror and a reference source that can be used for dynamic calibration.

[0030] Figure 11A Is a schematic view of a mobile infrared imaging system configured to be carried or worn by a human user.

[0031] Figure 11B Is a schematic view of an installation site that can be monitored by multiple infrared imaging systems.

[0032] Figure 12 Is a schematic system block diagram showing a mobile infrared imaging system according to one embodiment.

[0033] Figure 13A Is a schematic system diagram of an optical system configured to be used in the mobile infrared imaging system disclosed herein according to various embodiments.

[0034] Figure 13B Is a schematic system diagram of an optical system configured to be used in the mobile infrared imaging system disclosed herein according to other embodiments.

[0035] Figure 14A Is a schematic perspective view of a mobile infrared imaging system mounted to a helmet according to various embodiments.

[0036] Figure 14B Is Figure 14A An enlarged schematic perspective view of the mobile infrared imaging system shown in

[0037] Figure 14C Is Figure 14A - 14B A perspective cross-sectional view of the mobile infrared imaging system shown in

[0038] Figure 15A Is a schematic perspective view of a system according to various embodiments.

[0039] Figure 15B Is Figure 15A A schematic rear perspective view of the system shown in

[0040] Figure 15C Is a schematic front perspective view of a system according to various embodiments.

[0041] Figure 15DSchematic system diagram of a mobile computing device having a first port configured to be electrically and physically coupled to a divided-aperture infrared spectroscopy imaging (DAISI) system, according to various embodiments.

[0042] Figure 15E Schematic system diagram of a mobile computing device, according to various embodiments.

[0043] Figure 16A Schematic diagram of a DAISI system that can be used according to any of the embodiments disclosed herein.

[0044] Figure 16B Schematic front perspective view of a DAISI system, according to various embodiments, in which the housing is removed for illustrative purposes only.

[0045] Figure 16C Is Figure 16B Schematic rear perspective view of the DAISI system.

[0046] Figure 16D Is Figure 16B Schematic front perspective view of the optical system of the DAISI system.

[0047] Figure 16E Is Figure 16B Schematic perspective cross-sectional view of the optical system of the DAISI system, in which the shutter is omitted for illustrative purposes.

[0048] Figure 17A According to various embodiments Figure 16B And 16D Front plan view of the shutter shown in.

[0049] Figure 17B Schematic perspective exploded view of the shutter, according to some embodiments.

[0050] Figure 17C Is of the shutter in the closed configuration Figure 17B Front view of the shutter.

[0051] Figure 17D Is of the shutter in the open configuration Figure 17B And 17C Front view of the shutter.

[0052] Figure 18A And 18B Illustrate embodiments of an imaging system, according to various embodiments, the imaging system including a lens array formed of a monolithic lens substrate.

[0053] Figure 18CShows an embodiment of an imaging system according to various embodiments, the imaging system including a lens array formed by respective lens substrates.

[0054] Figure 18D Is an exploded perspective view of an imaging system having a lens array formed by respective lens substrates shown in Figure 18C The respective lens substrates shown in.

[0055] Figure 18E Is formed by Figure 18C And 18D A cross-sectional view of a lens assembly formed by respective lens substrates of the type shown in.

[0056] Figure 19 Is a schematic diagram of a patterned optical filter array that can be used in an imaging system having separate apertures according to various embodiments.

[0057] Figure 20A - 20C Illustrates an array of a filter body and individual optical filters that can be used in an imaging system having separate apertures according to various embodiments.

[0058] Figure 21 Shows a schematic system diagram of a mobile infrared imaging system including one or more optional cooling systems according to various embodiments.

[0059] Figure 22A Is a ray trace diagram illustrating an example of optical crosstalk between optical channels of a lens assembly according to various embodiments of Figure 18D The lens assembly.

[0060] Figure 22B Is an exploded perspective view of a lens assembly configured to at least partially reduce optical crosstalk and that can be used in conjunction with a DAISI system according to various embodiments.

[0061] Figure 22C Is a front schematic view of an optical detector depicting another example of optical crosstalk between adjacent optical channels and non-uniformity of the available image size due to the crosstalk according to various embodiments.

[0062] Figure 22D Depicts an illumination area of light transmitted from an object to an optical detector according to various embodiments, wherein the lens assembly can be configured to increase the available image area at the optical detector while reducing vignetting.

[0063] Figure 22E Is a front plan view of an exemplary lens assembly, the dimensions of the exemplary lens assembly being designed to transmit radiation to the Figure 22D Illumination area shown in.

[0064] Figure 22F It is cross Figure 22D Example simulation of intensity roll-off over the available area.

[0065] Figure 22G Illustrated are example vignetting of an image of a scene in accordance with various embodiments.

[0066] Figure 23A - 23D is a schematic side view of an athermalization system according to various embodiments.

[0067] Figure 24A is a schematic system diagram of a DAISI system that may include a motion compensation system according to various embodiments.

[0068] Figure 24B The diagram shows that only when the motion of the DAISI system is less than the motion threshold Figure 24A A graph of a set of example motor thresholds used by the DAISI system to activate itself.

[0069] Figure 24C is a flow chart illustrating an example method for compensating for motion of a DAISI system according to various embodiments.

[0070] Figure 24D is a graph of error distribution for the motion compensation systems and methods described herein, according to various embodiments.

[0071] Like numbers and designations throughout the various drawings indicate like elements. DETAILED DESCRIPTION

[0072] I. Overview of various embodiments

[0073] The following description is directed to certain embodiments used to describe the innovative aspects of the present disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The described embodiments can be implemented in any device, apparatus, or system that can be configured to operate as an imaging system, such as an infrared imaging system. The methods and systems described herein can be included in or associated with a variety of devices, such as, but not limited to, devices for visible and infrared spectra, multispectral and hyperspectral imaging devices used in oil and gas exploration, refining and transportation, agriculture, remote sensing, defense and homeland security, surveillance, astronomy, environmental monitoring, and the like. The methods and systems described herein can be applied in a variety of fields, including, but not limited to, agriculture, biology, physics, chemistry, defense and homeland security, environment, the oil and gas industry, and the like. The present teachings are not intended to be limited to only the embodiments depicted in the figures, but rather have broad applicability, as will be apparent to those skilled in the art.

[0074] The spectral image of a scene can be represented as a three-dimensional data cube, where two axes of the cube represent two spatial dimensions of the scene, and the third axis of the data cube represents the spectral information of the scene in different wavelength regions. Mathematical methods can be used to process the data cube to obtain information about the scene. Some existing spectral imaging systems generate the data cube by scanning the scene in the spatial domain (e.g., by moving a slit across the horizontal and vertical dimensions of the scene) and / or by scanning the scene in the spectral domain. Such a scanning scheme acquires only a part of the complete data cube at a time. These parts of the complete data cube are stored and then processed to generate the complete data cube.

[0075] Various embodiments disclosed herein describe a Dispersive Aperture Infrared Spectral Imaging (DAISI) system that is constructed and adapted to provide identification of target chemical components of an imaged scene. The system is based on spectral-resolved imaging and can provide such identification with a single shot (also referred to as a snapshot), which includes multiple images with different wavelength components that are typically obtained simultaneously. Without loss of generality, a snapshot refers to a system in which most of the data elements collected continuously view the light emitted from the scene. In contrast, in a scanning system, at any given time, only a few data elements continuously view the scene, followed by a different set of data elements, and so on until a complete data set is collected. Relatively fast operation can be achieved in a snapshot system because it does not require the use of spectral or spatial scanning to acquire the infrared (IR) spectral characteristics of the target chemical components. Instead, IR detectors (such as, for example, infrared focal plane arrays or FPAs) associated with multiple different optical channels having different wavelength distributions can be used to form a spectral cube of the imaging data. Although spectral data can be obtained from a single snapshot that includes multiple simultaneously acquired images corresponding to different wavelength ranges, in various embodiments, multiple snapshots can be obtained. In various embodiments, these multiple snapshots can be averaged. Similarly, in certain embodiments, multiple snapshots can be obtained, and a portion of these snapshots can be selected and averaged. Moreover, compared to commonly used infrared spectral imaging systems, the DAISI system does not require cooling. Thus, it can advantageously use uncooled infrared detectors. For example, in various embodiments, the imaging systems disclosed herein do not include a detector configured to be cooled to a temperature below 300 Kelvin (K). As another example, in various embodiments, the imaging systems disclosed herein do not include a detector configured to be cooled to a temperature below 273 K. As yet another example, in various embodiments, the imaging systems disclosed herein do not include a detector configured to be cooled to a temperature below 250 K. As another example, in various embodiments, the imaging systems disclosed herein do not include a detector configured to be cooled to a temperature below 200 K.

[0076] Embodiments disclosed herein offer several advantages over existing IR spectral imaging systems, most (if not all) of which may require a highly sensitive and cooled FPA to compensate for the reduction in photon flux caused by spectral scanning operations during optical detection. Highly sensitive and cooled FPA systems are expensive and require extensive maintenance. Because the various embodiments disclosed herein are configured to operate in a single-shot acquisition mode without spatial and / or spectral scanning, the instrument can receive photons from multiple points (e.g., every point) of an object substantially simultaneously during a single readout. Consequently, embodiments of the imaging systems described herein can collect significantly greater amounts of optical power (e.g., orders of magnitude more photons) from an imaged scene at any given moment, particularly compared to spatial and / or spectral scanning systems. Consequently, various embodiments of the imaging systems disclosed herein can operate using uncooled detectors (e.g., FPA units including microbolometer arrays), which are less sensitive to photons in the IR but are well-suited for continuous monitoring applications. For example, in various embodiments, the imaging systems disclosed herein do not include detectors configured to be cooled to temperatures below 300 Kelvin. As another example, in various embodiments, the imaging systems disclosed herein do not include detectors configured to be cooled to a temperature below 273 Kelvin. As yet another example, in various embodiments, the imaging systems disclosed herein do not include detectors configured to be cooled to a temperature below 250 Kelvin. As another example, in various embodiments, the imaging systems disclosed herein do not include detectors configured to be cooled to a temperature below 200 Kelvin. Imaging systems that include non-cooled detectors may be able to operate in extreme weather conditions, require less electricity, be able to operate during daytime and nighttime, and be less expensive. Some embodiments described herein may also be less susceptible to motion artifacts than spatial and / or spectral scanning systems that may cause errors in spectral data, spatial data, or both.

[0077] In various embodiments disclosed herein, the DAISI system can be mobile. For example, the DAISI system can be configured to be worn or carried by a person. For example, the DAISI system can be miniaturized to fit within a relatively small housing or compartment. For example, the size and shape of the components of the DAISI system can be designed to fit within small dimensions and can have a small enough mass to enable a human user to carry or wear the system without undue fatigue. As explained herein, in some embodiments, the size and shape of the DAISI system can be designed to fit within a volume of less than about 300 cubic inches, or in some embodiments, less than about 200 cubic inches. In still other embodiments, the size and shape of the DAISI system can be designed to fit within a volume of less than about 100 cubic inches. For example, in some arrangements, the size and shape of the DAISI system can be designed to fit within a volume ranging from about 50 cubic inches to about 300 cubic inches. In other arrangements, the size and shape of the DAISI system can be designed to fit within a volume ranging from about 80 cubic inches to about 200 cubic inches.

[0078] Advantageously, such a portable and / or wearable DAISI system can enable a user to monitor a facility at a remote location and detect the presence of various gases (e.g., toxic gases) in real time. Additionally, the portable DAISI system can enable a user to travel to different facilities to monitor the presence of gases or chemicals at multiple locations. For example, a user can travel to an oil drilling facility where oil is pumped from the ground. The user can carry or attach the portable DAISI system to his or her clothing or body (e.g., via a clip, hat, etc.), and can activate the system while he or she is at the site. The optical components onboard the portable DAISI system can capture one or more snapshot multispectral images of portions of the facility vulnerable to gas or chemical leaks. The computing unit onboard the portable DAISI system can process the captured multispectral image data to detect and / or classify the gases or chemicals present at the site. The communication module can notify the user of the detected gases. For example, in various embodiments, the communication module can send a notification to a user interface (such as a pair of computing glasses, a mobile computing device such as a mobile smartphone, a tablet computing device, a laptop computing device, or any other suitable interface), and the user interface can display information about the detected gases to the user in real time, e.g., at the oil drilling facility.

[0079] II. Examples of Split Aperture Infrared Spectral Imaging Systems

[0080] Figure 1Provided is a schematic illustration of the spatial and spectral partitioning of incoming light by an embodiment 100 of a Dispersive Aperture Infrared Spectral Imager (DAISI) system that can image an object 110 having one or more IR spectral signatures. System 100 includes a front objective 124, an optical filter array 130, a re-imaging lens array 128, and a detector array 136. In various embodiments, detector array 136 can include a single FPA or an FPA array. Each detector in detector array 136 can be disposed at the focal point of each lens in re-imaging lens array 128. In various embodiments, detector array 136 can include a plurality of photosensitive devices. In some embodiments, the plurality of photosensitive devices can include a two-dimensional imaging sensor array that is sensitive to radiation having wavelengths between 1 μm and 20 μm (e.g., in the near-infrared wavelength range, the mid-infrared wavelength range, or the long-infrared wavelength range). In various embodiments, the plurality of photosensitive devices can include a CCD or CMOS sensor, a bolometer, a microbolometer, or other detectors sensitive to infrared radiation.

[0081] The aperture of the system 100 associated with the front objective system 124 is spatially and spectrally divided by a combination of an optical filter array 130 and a re-imaging lens array 128. In various embodiments, the combination of the optical filter array 130 and the re-imaging lens array 128 can be considered to form a spectrally separated pupil, which is disposed in front of the optical detector array 136. The spatial and spectral division of the aperture into different aperture portions forms a plurality of optical channels 120 along which light propagates. In various embodiments, the array 128 of re-imaging lenses 128a and the spectral filter array 130 each correspond to a different optical channel 120. The plurality of optical channels 120 can be spatially and / or spectrally different. The plurality of optical channels 120 can be formed in object space and / or image space. In one embodiment, the different channels 120 can include optical channels that are angularly separated in space. The spectral filter array 130 may additionally include a filter-retaining aperture mask (comprising, for example, an IR light-blocking material such as ceramic, metal, or plastic). Light from an object 110 (e.g., a gas cloud) whose optical properties in the IR are described by a unique absorption, reflection, and / or emission spectrum is received through the aperture of the system 100. This light propagates through each of the plurality of optical channels 120 and is further imaged onto an optical detector array 136. In various embodiments, the detector array 136 may include at least one FPA. In various embodiments, each re-imaging lens 128a may be spatially aligned with a respective corresponding spectral region. In the illustrated embodiment, each filter element from the spectral filter array 130 corresponds to a different spectral region. Each re-imaging lens 128a and the corresponding filter element of the spectral filter array 130 may coincide with (or form a portion of) a separate aperture and, therefore, coincide with a respective corresponding spatial channel 120. Thus, in various embodiments, an imaging lens 128a and a corresponding spectral filter can be positioned in the optical path of one of the plurality of optical channels 120. Radiation propagating from object 110 through each of the plurality of optical channels 120 travels along the optical path of each re-imaging lens 128a and corresponding filter element of the spectral filter array 130 and is incident on a detector array (e.g., an FPA component) 136 to form a single image (e.g., a sub-image) of object 110. The image formed by detector array 136 typically includes multiple sub-images formed by each of the optical channels 120. Each of the multiple sub-images can provide different spatial and spectral information of object 110. Due to the different spatial locations of the smaller of the separate apertures, different spatial information results from some parallax. In various embodiments, adjacent sub-images can be characterized by similar or substantially equal spectral characteristics. Detector array (e.g., an FPA component) 136 is also operably connected to a processor 150 (not shown).Processor 150 can be programmed to aggregate data collected using system 100 into a spectral data cube. The data cube represents the overall spectral image of object 110 within a spectral region defined by a combination of filter elements in spectral filter array 130 in spatial (x,y) and spectral (λ) coordinates. Additionally, in various embodiments, processor or processing electronics 150 can be programmed to determine the unique absorption characteristics of object 110. Additionally, processor / processing electronics 150 can alternatively or additionally map the entire image data cube into a data cube representing the spatial distribution of the concentration c of a target chemical component, for example, within the field of view associated with object 110.

[0082] Various implementations of embodiment 100 can include an optional removable temperature-controlled reference source 160, which includes, for example, a shutter system including one or more reference shutters maintained at different temperatures. Reference source 160 can include a heater, a cooler, or a temperature control element configured to maintain reference source 160 at a desired temperature. For example, in various implementations, embodiment 100 can include two reference shutters maintained at different temperatures. Reference source 160 is removable and, in one implementation, is periodically inserted into the optical path of light passing through system 100 from object 110 to detector array (e.g., FPA component) 136 along at least one channel 120. Thus, removable reference source 160 can block such an optical path. Additionally, the reference source 160 can provide a reference IR spectrum to recalibrate various components including detector array 136 of system 100 in real time. The configuration of removable reference source 160 is discussed further below.

[0083] In embodiment 100, front objective system 124 is shown as including a single front objective lens positioned to establish a common field of view (FOV) for re-imaging lens 128a and define an aperture stop for the entire system. In this particular case, the aperture stop is substantially spatially coincident with and / or approximately the same size or slightly larger than a plurality of smaller limiting apertures corresponding to different optical channels 120. Thus, the positions of the spectral filters for the different optical channels 120 coincide with the position of the aperture stop for the entire system, which in this example is shown as a surface between lens system 124 and array 128 of re-imaging lenses 128a. In various embodiments, lens system 124 can be objective lens 124. However, objective lens 124 is optional, and various embodiments of system 100 need not include objective lens 124. In various embodiments, objective lens 124 can slightly spatially offset the images obtained by different detectors in array 136 along a direction perpendicular to the optical axis of lens 124, so the functionality of system 100 is not necessarily impaired when objective lens 124 is not included. However, in general, the field apertures corresponding to different optical channels can be located in the same or different planes. In certain embodiments, these field apertures can be defined by the aperture of re-imaging lens 128a and / or by filters 130 in separate apertures. In one embodiment, the field apertures corresponding to different optical channels can be located in different planes, and the different planes can be optically conjugate to each other. Similarly, while all filter elements in spectral filter array 130 of embodiment 100 are shown as being located in one plane, generally different filter elements of spectral filter array 130 can be arranged in different planes. For example, different filter elements of spectral filter array 130 can be arranged in different planes that are optically conjugate to each other. However, in other embodiments, different filter elements can be arranged in non-conjugate planes.

[0084] In contrast to embodiment 100, the front objective lens 124 need not be a single optical element, but may include a plurality of lenses 224, such as Figure 2 1. The front objective lenses 224 are configured to divide the incoming optical wavefront from the object 110. For example, an array of front objective lenses 224 can be arranged to receive the IR wavefront emitted by the object and directed toward the DAISI system. The plurality of front objective lenses 224 spatially divide the wavefront into non-overlapping intervals. Figure 2 Three objective lenses 224 are shown in the front optical portion of the optical system, which facilitate spatial division of the aperture of the system in this example. However, multiple objective lenses 224 can be configured as a two-dimensional (2D) lens array. Figure 2 A general view of the imaging system 200 and the resulting field of view of the imaging system 200 are presented. Figure 2An exploded view 202 of the imaging system 200 is also depicted in more detail in the illustration of FIG. As shown in the detailed view 202, an embodiment of the imaging system 200 includes a field reference 204 at the front end of the system. The field reference 204 can be used to truncate the field of view. Figure 2 The configuration shown has advantages over Figure 1 Embodiment 100 provides operational advantages because the overall size and / or weight and / or manufacturing costs of embodiment 200 can be significantly reduced due to the smaller objective lenses. Each pair of lenses in array 224 and array 128 is associated with a field of view (FOV). Each pair of lenses in array 224 and array 128 receives light from the object from a different angle. Therefore, the FOVs of different lens pairs in array 224 and array 128 do not completely overlap due to parallax. As the distance between imaging system 200 (portion 202) and object 110 increases, the overlap area 230 between the FOVs of individual lenses 224 increases, while the amount of parallax 228 remains approximately the same, thereby reducing its impact on system 200. When the ratio of parallax to object distance is substantially equal to the ratio of pixel size to system focal length, the parallax effect can be considered negligible and is no longer distinguishable for practical purposes. Although lenses 224 are shown as being arranged substantially in the same plane, the optional different objective lenses in the array of front objective lenses 224 can be arranged in more than one plane. For example, some individual lenses 224 may be shifted along axis 226 (not shown) relative to some other individual lenses 224 and / or have different focal lengths than some other lenses 224. As discussed below, field reference 204 may be used to calibrate plurality of detectors 236.

[0085] In one embodiment, a front objective system, such as lens array 224, is configured as a lens array that is integrated or molded in association with a monolithic substrate. Such an arrangement can reduce the cost and complexity that would otherwise be associated with optical adjustment of individual lenses within the system. Each lens 224 can optionally include lenses with varying magnifications. As an example, a pair of thin, large-diameter Alvarez plates can be used in at least a portion of the front objective system. Without loss of generality, the Alvarez plates can produce a change in focal length when the Alvarez plates are translated orthogonally relative to the light beam.

[0086] Further references Figure 1, a detector array 136 (e.g., an FPA component) configured to receive optical data representing the (one or more) spectral characteristics of the imaged object 110 may be configured as a single imaging array (e.g., an FPA) 136. This single array may be adapted to simultaneously acquire more than one image (formed by more than one optical channel 120). Alternatively, the detector array 136 may include FPA units. In various embodiments, the FPA units may include multiple optical FPAs. At least one of these multiple FPAs may be configured to acquire more than one spectrally distinct image of the imaged object. For example, as Figure 2 shown in embodiment 200, in various embodiments, the number of FPAs included in the FPA unit may correspond to the number of front objective lenses 224. In Figure 2 embodiment 200, for example, three FPAs 236 corresponding to three objective lenses 224 are provided. In one embodiment of the system, the FPA unit may include a microbolometer array. The use of multiple microbolometers advantageously allows for an inexpensive way to increase the total number of detection elements (i.e., pixels) used to record a three-dimensional data cube in a single acquisition event (i.e., one snapshot). In various embodiments, the microbolometer array more efficiently utilizes the detector pixels of the FPA array (e.g., each FPA) because when using a single microbolometer, the number of unused pixels is reduced, minimized, and / or eliminated between the possible images.

[0087] Figure 3A Schematically illustrates an embodiment 300 of an imaging system, where the number of front objective lenses 324a in the lens array 324, the number of relay lenses 128a in the lens array 128, and the number of FPAs 336 are the same. Configured in this way, each combination of the respectively corresponding front objective lens 324, relay lens 128a, and FPA 336 constitutes an individual imaging channel. This channel is associated with the acquisition of IR light emitted from the object 110 through individual filter elements of the optical filter array 130. The field reference 338 of the system 300 is configured to have a uniform temperature across its surface and is characterized by a predetermined spectral curve of the radiation emitted therefrom. In various embodiments, the field reference 338 may be used as a calibration target to assist in calibrating or maintaining the calibration of the FPA. Thus, in various embodiments, the field reference 338 is used to dynamically adjust the data output from each FPA 336 after light is acquired from the object 110. This dynamic calibration process helps to provide that the outputs of different (e.g., most or each) FPAs 336 represent correct acquisition data relative to other FPAs 336 used for analysis, as discussed in more detail below.

[0088] Figure 3B Illustrates perpendicular to Figure 3AA plan view of the axis 226 of the embodiment of the imaging system 300 is shown in FIG. Figure 3B In the illustrated embodiment, the optical components (e.g., objective lens 324a, filter elements of spectral filter array 130, re-imaging lens 128a, and FPA unit 336) are arranged in a 4x3 array. In one embodiment, the 4x3 array 340 of optical components (lenses 324a, 128a; detector elements 336) is used behind a temperature-controlled reference target 160. The field reference aperture 338 can be adapted to obscure and / or block peripheral portions of a light beam propagating from object 110 toward FPA unit 336. Thus, field reference 338 obscures and / or blocks the boundaries or peripheral portions of the image of object 110 formed on FPA elements positioned along perimeter 346 of the detector system. Generally, when two elements of an FPA unit are used to observe the same portion of a scene in the same spectral region using the same optical train, they will produce substantially equal digital count values. If any of these input parameters (e.g., the scene to be observed, the spectral content of the light from the scene, or the optical elements transmitting light from the scene to the two detector elements) are different, then the counts associated with the elements of the FPA unit will also be different. Thus, and by way of example, in two FPAs (such as Figure 3B With the FPAs (those represented as #6 and #7 in the figure) remaining substantially unobstructed by field reference 338, the output from these FPAs can be dynamically adjusted to the output from one of the FPAs positioned along perimeter 346 that processes light with similar spectral characteristics (such as, for example, FPA element #2 or FPA element #11).

[0089] Figure 4A portion of another embodiment of an imaging system 400 including an array 424 of front objective lenses 424a is schematically illustrated. The array 424 of lenses 424a is adapted to receive light from an object 110 and relay the received light to the array 128 of re-imaging lenses 128a via an array 438 of field references (or field stops) 438a and via an array 440 of relay lenses. The spectral characteristics of the field references / field stops 438a may be known. The field references 438a are positioned at corresponding intermediate image planes defined by respective front objective lenses 424a relative to the object 110. When the refractive characteristics of all front objective lenses 424a are substantially identical, all field references 438a are positioned in the same plane. The field references 438a of the array 438 mask (or cast a shadow on) the peripheral regions of corresponding images (e.g., sub-images) formed at a detector plane 444 by respective corresponding spatial imaging channels 450 of the system 400 before the images are spectrally processed by the processor 150. Relay lens array 440 then transmits light along each imaging channel 450, through a different spectral filter 454a of filter array 454, through a calibration device including two temperature-controlled shutters 460a, 460b, and then onto detector module 456. In various embodiments, detector module 456 may include an array of microbolometers or some other IR FPA.

[0090] Embodiment 400 has several operational advantages. It is configured to provide a spectrally known object within each image (e.g., sub-image) and for each snapshot acquisition to which calibration can be performed. This spectral certainty can be advantageous when using an array of IRFPAs such as microbolometers, whose detection characteristics can vary from one imaging frame to the next due, in part, to changes in the scene being imaged and thermal effects caused by adjacent FPAs. In various embodiments, the field reference array 438 of embodiment 400 can be set within a Rayleigh range associated with the front objective 424 (roughly corresponding to the depth of focus), thereby removing blurred pixels that are unavailable due to having a field reference outside of this range. In addition, Figure 4 The embodiment 400 may be compared to, for example Figure 3A The configuration of 300 is more compact. Figure 3A In the system shown, for example, field reference 338 may be separated from lens array 324 by a distance greater than several (eg, five) focal lengths to minimize / reduce blurring contributed by the field reference to the image formed at the detector plane.

[0091] In various embodiments, the multi-optical FPA unit of the IR imaging system may additionally include an FPA configured to operate in the visible portion of the spectrum. Figure 1For example, an image of a scene of interest formed by such a visible light FPA can be used as a background to form a composite image by overlaying an IR image with a visible light image. The IR image can be virtually overlaid using a processor and a specially designed computer program product, enabling such data to be processed by a viewer, either virtually or physically. The IR image can be created based on image data acquired by each FPA 136. The composite image thus formed helps identify the precise spatial location of a target substance, and the system can detect / identify the spectral signature of the target substance.

[0092] Optical filter

[0093] Optical filters used with embodiments of the system to define spectrally distinct IR images (e.g., sub-images) of an object may employ absorption filters, interference filters, and filters based on Fabry-Perot etalons, to name a few. When interference filters are used, the spectral image is obtained by the respective re-imaging lenses (e.g., Figure 1 、 2 Image acquisition of the individual imaging channels defined by the lenses 128a) in , 3 and 4 can be performed in a single spectral bandwidth or in multiple spectral bandwidths. Figures 1 to 4 Embodiments 100, 200, 300, 400, and further reference Figure 3B , Figure 5A and 5B An example of a 4 by 3 array 130 of spectral filters is shown in FIG. Each filter 1 to 12 is juxtaposed with supporting optomechanical elements (not shown) to define a filter array plane that is oriented substantially perpendicular to the general optical axis 226 of the imaging system in operation. In various embodiments, each filter 1 to 12 need not be a discrete optical component. Instead, each filter 1 to 12 may comprise one or more coatings applied to a re-imaging lens such as a Figure 1 、 2 , 3 and 4) or one or more surfaces of the lens 128a) or the surface of one or more detectors.

[0094] The optical filtering configurations of the various embodiments disclosed herein can advantageously utilize bandpass filters that define a specific spectral band. For example, a filter having a transmission curve such as Figure 6A Any of the filters 0a to 3a shown. The filter may be placed in front of the optical FPA (or generally between the optical FPA and the object). In particular, and with further reference to Figure 1 、 2, 3, and 4, when the optical detector arrays 136, 236, 336, and 456 include microbolometers, the primary contribution to noise associated with image acquisition is due to detector noise. To compensate for and / or reduce noise, various embodiments disclosed herein utilize spectral multiplexing filters. In various implementations, the spectral multiplexing filters can include multiple long-pass filters, multiple long-pass filters, multiple band-pass filters, and any combination thereof. Figure 6B Examples of spectral transmission characteristics of spectral multiplexing filters 0b to 3d for use with various embodiments of the imaging systems disclosed herein are depicted in FIG. Figure 6C The filter may be referred to as a long-pass LP filter. LP filters generally attenuate shorter wavelengths and transmit (pass) longer wavelengths (e.g., within the effective range of the target IR portion of the spectrum). In various embodiments, a short-pass SP filter may also be used. SP filters generally attenuate longer wavelengths and transmit (pass) shorter wavelengths (e.g., within the effective range of the target IR portion of the spectrum). Due, at least in part, to the snapshot / non-scanning mode of operation, embodiments of the imaging system described herein can use a less sensitive microbolometer without compromising SNR. Using a microbolometer as a detector noise-limited device not only benefits from the use of spectral multiplexing filters, but also eliminates the need to cool the imaging system during normal operation.

[0095] Reference again Figure 6A 、 6B , 6C, and 6D, each filter (0b...3d) transmits light across a substantially wider region of the electromagnetic spectrum than the region of the electromagnetic spectrum of filters (0a...3a). Thus, when the spectrally multiplexed filter set (0b...0d) is used with an embodiment of an imaging system, the total amount of light received by the FPA (e.g., 236, 336) is greater than the amount of light that would be received when bandpass filters (0a...4a) are used. This "added" transmission of light confined by the use of spectrally multiplexed LP (or SP) filters helps increase the signal at the FPA to a level above the detector noise. Furthermore, by using filters having a spectral bandwidth greater than that of the bandpass filters in embodiments of the imaging system, the uncooled FPA of embodiments of the imaging system experiences less heating from radiation incident on it from the imaging scene and from radiation originating from the FPA itself. This reduced heating is due to reduced thermal emission from back-reflection(s) of the FPA and reflections from non-bandpass regions of the filter. Due to the wide transmission area of the multiplexed LP (or SP) filter, this parasitic effect is reduced, thereby improving the overall performance of the FPA unit.

[0096] In one embodiment, the LP and SP filters may be combined in a spectrally multiplexed fashion to increase or maximize the spectral range of the transmission region of the filter system of the embodiment.

[0097] The advantages of using spectrally multiplexed filters can be appreciated based on the following derivation, where a system of M filters is examined (however, it should be understood that embodiments of the present invention may employ any number of filters in practice). As an illustrative example, consider the case where M = 7. The analysis given below pertains to one spatial location in each image (e.g., sub-image) formed by different imaging channels (e.g., different optical channels 120) in the system. A similar analysis can be performed for each point in the image (e.g., sub-image), and thus the analysis can be extended appropriately as needed.

[0098] The amount of unknown light within each of the M spectral channels (corresponding to these M filters) is denoted by f1, f2, f3,... f M and the readings of the corresponding detector elements that receive the light transmitted by each filter are denoted as g1, g2, g3... g M , while the measurement errors are denoted by n1, n2, n3,... n M . Then, the readings at seven FPA pixels, each optically filtered by the corresponding bandpass filter through Figure 6A , can be represented as follows:

[0099] g1 = f1 + n1,

[0100] g2 = f2 + n2,

[0101] g3 = f3 + n3,

[0102] g4 = f4 + n4,

[0103] g5 = f5 + n5,

[0104] g6 = f6 + n6,

[0105] g7 = f7 + n7,

[0106] These readings (pixel measurements) g i are estimates of the spectral intensity f i . Due to the measurement error n i , the estimate g i is not equal to the corresponding f i value. However, if the measurement noise distribution has a zero mean, then the overall average of each individual measurement can be considered equal to the true value, i.e., (g i ) = f i . Here, the angled brackets indicate the operation of calculating the overall average of a random variable. Thus, the variance of the measurement can be expressed as:

[0107]

[0108] In embodiments that utilize a spectral multiplexing filter, compared to embodiments that utilize a bandpass filter, the amount of radiant energy transmitted by each spectrally multiplexed LP or SP filter to a given detector element can exceed the amount of radiant energy transmitted through the spectral band of a bandpass filter. In such cases, the intensity of light corresponding to individual spectral bands can be reconstructed by computational means. Such embodiments can be referred to as "multiplexed designs."

[0109] One matrix for measurements with such "multiplexing filters" includes a Hadamard matrix that requires "negative" filters, which may not necessarily be suitable for the optical embodiments disclosed herein. The S-matrix method (which is limited to numbers of filters that are integers equal to one less than a multiple of 4) or the row-doubled Hadamard matrix (which requires the number of filters to be an integer multiple of 8) can be used in various embodiments. Here, the possible numbers of filters using the S-matrix setup are 3, 7, 11, etc., and if the row-doubled Hadamard matrix setup is used, the possible numbers of filters are 8, 16, 24, etc. For example, the goal of the measurement can be to measure the intensity of 7 spectral bands f i using the following 7 measurement values g i :

[0110] g1 = f1 + 0 + f3 + 0 + f5 + 0 + f7 n1

[0111] g1 = 0 + f2 + f3 + 0 + 0 + f6 + f7 + n2

[0112] g3 = f1 + f2 + 0 + 0 + f5 + 0 + f7 + n3

[0113] g4 = 0 + 0 + 0 + f4 + f5 + f7 + f8 + n4

[0114] g5 = f1 + 0 + f3 + f4 + 0 + f6 + 0 + n5

[0115] g6 = 0 + f2 + f3 + f4 + f5 + 0 + 0 + n6

[0116] g7 = f1 + f3 + 0 + f4 + 0 + 0 + f7 + n7

[0117] The light transmission characteristics of the filters described above are plotted in Figure 6B . Here, the relationship analogous to (g i ) = f i no longer provides a solution for f iAlternatively, if a “hat” notation is used to express an estimate of a given value, a linear combination of the measured values can be used, such as, for example,

[0118]

[0119] These Is when n i is an unbiased estimate of a zero-mean random variable, such that The measurement variance corresponding to the i-th measurement is given by:

[0120]

[0121] From the above equation, it is observed that by employing a spectral multiplexing system, the signal-to-noise ratio (SNR) of the measurement is improved by times.

[0122] For N channels, the SNR improvement achieved using a spectral multiplexing system can be expressed as For example, embodiments employing 12 spectral channels (N=12) are characterized by SNR improvements over non-spectrally multiplexed systems, including improvements of up to 1.88 times.

[0123] Two additional examples of related spectral multiplexing filter arrangements 0c to 3c and 0d to 3d that may be used in various embodiments of the imaging systems described herein are provided in Figure 6C and 6D Shown in. Figure 6C and 6D The spectral multiplexing filter shown in can be used in embodiments of imaging systems employing uncooled FPAs, such as microbolometers. Figure 6C A set of spectrally multiplexed longpass (LP) filters used in the system is illustrated. LP filters generally attenuate shorter wavelengths and transmit (pass) longer wavelengths (e.g., within the effective range of the target IR portion of the spectrum). A single spectral channel having a transmission characteristic corresponding to the difference between the spectral transmission curves of at least two of these LP filters can be used to obtain imaging data for a data cube using embodiments of the system described herein. In various embodiments, the spectral filters positioned relative to different FPAs can have different spectral characteristics. In various embodiments, the spectral filters can be positioned only in front of some of the FPAs, while the remaining FPAs can be configured to receive unfiltered light. For example, in some embodiments, only 9 of the 12 detectors in the 4x3 detector array described above can be associated with spectral filters, while the other 3 detectors can be configured to receive unfiltered light. Such a system can be configured to acquire spectral data in 10 different spectral channels in a single data acquisition event.

[0124] Using a microbolometer as a detector noise-limited device can not only benefit from the use of a spectral multiplexing filter, but also does not require cooling the imaging system during normal operation. Compared with an imaging system including a high-sensitivity FPA unit with reduced noise characteristics, embodiments of the imaging system described herein can employ a less sensitive microbolometer without compromising the SNR. This result is at least partially attributed to the snapshot / non-scanning operation mode.

[0125] As discussed above, embodiments can optionally and in addition to a temperature-controlled reference unit (e.g., a temperature-controlled shutter such as shutters 160, 460a, 460b), employ a field reference component (e.g., Figure 3A field reference aperture 338 in Figure 4 or an array of field reference components (e.g.,

[0126] Specifically, and with further reference to Figure 1 、 2 、3 and 4, the temperature-controlled unit typically employs a system having a first temperature zone and a second temperature zone maintained at a first different temperature and a second different temperature. For example, the shutter system of each of embodiments 100, 200, 300, and 400 can employ not one but at least two temperature-controlled shutters that are substantially parallel to each other and transverse to the general optical axis 226 of (one or more) of embodiments 100, 200, 300, 400. Two shutters at two different temperatures can be employed to provide more calibration information; for example, the absolute value of the difference between FPAs at one temperature and the variation of this difference with temperature can be recorded. For example, with reference to Figure 4, which shows such a multi-shutter structure. Using multiple shutters enables the user to create a known reference temperature difference sensed by the FPA 456. When these shutters are positioned to block the radiation from the object 110, the IR radiation emitted by the shutter(s) 460a, 460b provides this reference temperature difference. Thus, not only can the offset value corresponding to each of the individual FPA pixels be adjusted, but also the gain value of these FPAs can be adjusted. In an alternative embodiment, a system having a first temperature zone and a second temperature zone may include a single or multiple components. The single or multiple components may include, for example, a plate. The component can be mechanically moved on the optical axis by using appropriate guides and has a first part at a first temperature and a second part at a second temperature.

[0127] In fact, the calibration process of an embodiment of the imaging system begins with estimating the gain and offset by performing measurements of the radiation emitted independently from at least two temperature-controlled shutters of known and different radiations. The gain and offset can vary between detector pixels. Specifically, first, the response of the detector unit 456 to the radiation emitted from one shutter is performed. For example, the first shutter 460a blocks the FOV of the detector 456, and the temperature T1 is directly and independently measured using a thermistor. After such an initial measurement, the first shutter 460a is removed from the optical path of the light passing through the embodiment, and another second shutter (e.g., 460b) is inserted in its position on the optical axis 226 to prevent light from propagating through the system. The temperature of the second shutter 460b can be different from that of the first shutter (T2≠T1). The temperature of the second shutter 460b is also independently measured using a thermistor placed in contact with the shutter, and the response of the detector to the radiation emitted from the shutter 460b is also recorded. Representing the operational response (expressed in digital or "counts") of the FPA pixel as g i to the source of radiation L i , the readings corresponding to the measurements of the two shutters can be expressed as:

[0128] g1 = γL1(T1) + g offset

[0129] g2 = γL2(T2) + g offset

[0130] Here, g offset is the pixel offset value (in counts), and γ is the pixel gain value (in counts per unit of radiation). If the values of g1 and g2 and the radiation values L1 and L{2} are available, these two equations can be solved for the two unknowns g offsetSolutions for and γ. For example, these values can be measured by a reference instrument or calculated from known temperatures T1 and T2 together with the known spectral responses of the FPA and the optical system. For any subsequent measurement, the above equation(s) can then be inverted to estimate the radiation value of the object from the detector measurement, and this can be done for each pixel in each FPA within the system.

[0131] As already discussed, and referring to Figures 1 to 4 , the field reference aperture can be set in the object space or the image space of the optical system, and the dimensions are designed to block a specific portion of the IR radiation received from the object. In various embodiments, the shape of the opening of the field reference aperture can be substantially similar to the boundary of the filter array (e.g., and referring to Figure 3B , 5B 's filter array - e.g., rectangular). The field reference aperture can be placed in front of the objective lens (124, 224, 324, 424), and the distance is at least several times the focal length of the lens (in one embodiment - at least five times) such that the field reference aperture is placed closer to the object. Placing the field reference aperture closer to the object can reduce image blurring. In Figure 4 's Example 400, the field reference aperture can be placed within the depth of focus of the image conjugate plane formed by the front objective lens 424. Generally, the field reference can reference and stabilize the outputs of different FPAs in the array by providing an object with a known spectrum and stable over time within each scene, thereby facilitating, enabling, and / or allowing for dynamic compensation in the system.

[0132] Since the offset value of each FPA is typically adjusted from frame to frame by the hardware, comparing the output of one FPA with the output of another FPA may have errors that cannot be compensated by the established static calibration parameters g offset and γ (e.g., by the movable shutter 160). To ensure that the FPA operates within the radiation measurement protocol over time, it is advantageous to have a portion of each detector array view a reference source (e.g., such as the field reference 338 in Figure 3A ) over multiple frames obtained over time. If the reference source spectrum is known a priori (such as a blackbody source at a known temperature), then the response of each FPA to the reference source can be measured to estimate the change in the pixel offset value. However, the temperature of the reference source does not need to be known. In such an embodiment, the dynamic calibration of different detectors can be performed by monitoring the changes in the gain and offset of various detectors starting from the time when the movable shutter used for static calibration is removed. An example calculation of the dynamic offset is performed as follows.

[0133] Among the FPA elements in the FPA array in an embodiment of the imaging system, one FPA can be selected as the "reference FPA". The field reference temperature measured by all other FPAs can be adjusted to be consistent with the field reference temperature measured by the reference, as discussed below. The image obtained by each FPA includes a set of pixels blocked by the field reference 338. Using the previously obtained calibration parameters g offset and γ (pixel offset and gain), the following equation is used to estimate the effective blackbody temperature T of the field reference as measured by each FPA i :

[0134] T i = mean{(g + Δg i + g offset / γ} = mean{(g offset ) / γ} + ΔT i

[0135] Using the above equation, the average value over all pixels blocked by the field reference is obtained. In the above equation, Δg i is the difference between the offset value of the current frame and the Δg offset obtained during the calibration step. For the reference FPA, Δg i can simply be set to zero. Then, using the temperature difference measured by each FPA, the following is obtained:

[0136] T i - T ref = mean{(g + Δg i + g offset / γ} + ΔT i - mean{(g - g offset ) / γ} = ΔT i

[0137] Once the ΔT i of each FPA is measured, its value can be subtracted from each image to force the operation between this FPA and the reference FPA to be consistent. Although the calibration process has been discussed above with reference to the calibration of temperature, a calibration method for radiation values that is procedurally similar can also be implemented.

[0138] Example of measurement method

[0139] Before optical data acquisition using an embodiment of the IR imaging system as described herein, one or more, most, or possibly all of the FPAs of the system can be calibrated. For example, more than 50%, 60%, 70%, 80%, or 90% of the FPAs 336 can be initially calibrated. As Figure 3AAs shown, these FPAs 336 can form separate images of an object using light transmitted in corresponding optical channels, which can include a combination of a corresponding front objective lens 324 and a re-imaging lens 128. A calibration process can allow the individual images to be formed in equivalent units (such that, for example, the readings of the FPA pixels can be recalculated in units of temperature or radiation, etc.). Additionally, the calibration process can also allow the FPAs (e.g., each FPA) to be spatially co-registered with each other, such that a given pixel of a particular FPA can be optically remapped by the optical system to the same location on the object as a corresponding pixel of another FPA.

[0140] To achieve at least some of these goals, a spectral differencing approach can be employed. This approach involves forming a differential image from various combinations of images from different channels. In particular, the images used to form the differential image can be registered by two or more different FPAs in spectrally different channels, each having different spectral filters with different spectral characteristics. Images from different channels with different spectral characteristics will provide different spectral information. Therefore, comparing (e.g., subtracting) these images can yield valuable spectral-based information. For example, if a filter element of the spectral filter array 130 corresponding to a particular FPA 336 transmits light from an object 110 that includes a gas cloud (e.g., having a spectrum that includes a gas absorption peak or a gas emission peak), while another filter element of the spectral filter array 130 corresponding to another FPA 336 does not transmit that spectrum, then the difference between the images formed by the two FPAs in question will highlight the presence of the gas in the differential image.

[0141] A disadvantage of spectral difference methods is that contributions from some ancillary features associated with imaging (not just the target species, such as the gas itself) can also be prominent in and contribute to the difference image. To name a few, such contributing effects include parallax-induced imaging of the object's edges, the effects of magnification differences between two or more optical channels, and differences in rotational positioning and orientation between FPAs. While magnification-related errors and FPA rotation-induced errors can be compensated for by improving the accuracy of the instrument construction and through post-processing of the acquired imagery, parallax is scene-dependent and not easily corrected. Furthermore, spectral difference methods are susceptible to radiometric calibration errors. Specifically, for example, if one FPA registers the radiation from light of a given object feature as having a temperature of 40°C, while data from another FPA indicates a temperature of 39°C for the same object feature, then due to this radiometric calibration error, that object feature will be enhanced or highlighted in the difference image (formed at least in part based on the images provided by the two FPAs).

[0142] One solution to some of these problems is to compare (e.g., subtract) images from the same FPA acquired at different times. For example, an image can be compared to or subtracted from a reference image acquired at another time. Such a reference image, subtracted from other, later-acquired images, can be referred to as a temporal reference image. This solution can also be applied to spectral difference images. For example, image data generated from a spectral difference image can be normalized by data corresponding to the temporal reference image. For example, the temporal reference image can be subtracted from the spectral difference image to obtain a temporal difference image. For the purposes of this disclosure, this process is referred to as a temporal difference algorithm or method, and the resulting image of subtracting the temporal reference image from another image (such as a spectral difference image) is referred to as a temporal difference image. In some embodiments employing spectral differencing, a temporal reference image can be formed, for example, by creating a spectral difference image from two or more images registered by two or more FPAs at a single time. This spectral difference image is then used as the temporal reference image. The temporal reference image can then be subtracted from other, later-acquired images to provide a normalization that can be used to subtract or remove various errors or detrimental effects. For example, the results of the algorithm are not affected by a priori knowledge of whether an object or scene contains a target substance (such as a gas of interest) because the algorithm can highlight changes in scene characteristics. Therefore, as discussed above, a spectral difference image can be calculated from multiple spectral channels based on a snapshot image acquisition at any later time, and the spectral difference image can be subtracted from the time reference image to form a time difference image. Therefore, the time difference image is a normalized difference image. The difference between the two images (the time difference image) can highlight the target substance (gas) within the normalized difference image because such substance is not present in the time reference frame. In various embodiments, more than two FPAs can be used to align both the time reference image and the later acquired difference images to obtain a better SNR quality factor. For example, if two FPAs are associated with spectral filters with the same spectral characteristics, then the images acquired by the two FPAs can be combined after they have been aligned to obtain a better SNR factor.

[0143] While temporal differencing methods can be used to mitigate or eliminate some of the drawbacks of spectral differencing, they can introduce their own undesirable problems. For example, temporal differencing of imaging data is less sensitive to errors caused by calibration and parallax than spectral differencing of imaging data. However, any changes in the imaged scene that are unrelated to the target substance of interest (such as a specific gas) are highlighted in the temporal differencing image. Consequently, such changes in the imaged scene may be mistakenly perceived as the location of the target substance, thereby triggering errors in the detection of the target substance. For example, if the temperature of the background against which the gas is detected changes (due to natural cooling over time or due to the increase in the number of people, animals, or other objects passing through the FOV of the IR imaging system), this temperature change will produce a signal difference compared to measurements taken at an earlier time. Consequently, changes in scene temperature (caused by a cooling object, a person walking, etc.) may appear as detected target substances (such as gases). Consequently, attempts to compensate for operational differences between the individual FPAs in a multi-FPA IR imaging system using spectral or temporal differencing methods can introduce additional problems that can lead to erroneous detection of target substances. These issues include detection errors caused by scene motion that are difficult to correct and / or cannot be compensated for, and errors caused by parallax. Therefore, there is a need to compensate for image data acquisition and processing errors caused by motion of elements within the imaged scene.Various embodiments of the data processing algorithms described herein address and satisfy the need to compensate for such motion-induced and parallax-induced image detection errors.

[0144] In particular, in order to reduce or minimize the parallax-induced differences between images produced with two or more predetermined FPAs, a further difference image formed from images from at least two different FPAs may be used to estimate the parallax effect. The parallax error may be determined by comparing images from two different FPAs where the position between the FPAs is known. The parallax may be calculated based on the known relative position difference. The difference between the images from the two FPAs may be attributable to parallax, particularly if the FPAs have the same spectral characteristics, e.g. have the same spectral filters or neither has a spectral filter. However, parallax error correction may still be obtained from two FPAs with different spectral characteristics or spectral filters, particularly if the different spectral characteristics, e.g. the transmission spectra of the respective filters, are known and / or negligible. It may be useful to use two or more FPAs or FPAs at different locations, such as FPAs that are spaced further apart. For example, when using the outermost two cameras in an array, such as, for example, corresponding to Figure 5A When performing spectral differentiation of image data by taking the difference between the images collected by filters 2 and 3 in the filter array of the FPA, a differential image called "difference image 2-3" is formed. In this case, the alternative "difference image 1-4" is additionally formed by, for example, corresponding toFigure 5A Image data collected by alternative FPAs using filters 1 and 4 is formed. Assuming or ensuring that both alternative FPAs have approximately the same spectral sensitivity to the target substance, the alternative "difference images 1-4" will highlight pixels corresponding to features in the image caused by parallax. Therefore, based on the positive determination that the same pixels are highlighted in the spectral "difference images 2-3" used for target substance detection, it can be concluded that the image features corresponding to these pixels are likely caused by parallax rather than the presence of the target substance in the imaged scene. It should be noted that when using a single FPA or multiple FPAs as discussed above, parallax compensation can also be performed using the images created by the individual re-imaging lenses 128a. FPAs spaced apart in different directions can also be useful. More than two, for example, three or four or more FPAs can be used to establish parallax for parallax correction. In some embodiments, two central FPAs and one corner FPA are used for parallax correction. In some embodiments, these FPAs can have substantially similar or identical spectral characteristics, for example, having filters with similar or identical transmission spectra or no filters at all.

[0145] Another capability of the embodiments described herein is the ability to perform volume estimation of gas clouds. This can be achieved by exploiting (instead of compensating for or negating) the parallax-induced effects described above. In this case, the measured parallax between two or more images of similar spectral response (e.g., two or more channels or FPAs) can be used to estimate the distance between the imaging system and the gas cloud, or between the imaging system and an object in the system's field of view. The parallax-induced lateral image shift d between the two images is related to the distance z between the cloud or object 110 and the imaging system according to the equation z = -sz' / d. Here, s is the separation between the two images of similar spectral response, and z' is the distance from the rear lens to the image plane. The value of z' is typically approximately equal to the focal length f of the imaging system's lens. Once the distance z between the cloud and the imaging system is calculated, the size of the gas cloud can be determined based on the magnification m = f / z, where each image pixel Δx' on the gas cloud corresponds to a physical dimension Δx = Δx' / m in object space. To estimate the volume of the gas cloud, a certain symmetry of the cloud thickness based on the physical dimensions of the cloud can be assumed. For example, the cloud image can be rotated about a central axis passing through the cloud image to create a three-dimensional volume estimate of the gas cloud size. It is noteworthy that in the embodiments described herein, only a single imaging system is required to perform this volume estimation. In fact, due to the fact that information about the angle from which the system sees the gas cloud is decoded in the parallax effect, the image data includes information about the imaged scene associated with at least two angles as viewed by the system.

[0146] When a temporal difference algorithm is used to process the acquired imaging data, it may inadvertently highlight scene changes in the resulting image that are not caused by the target substance. In various embodiments, compensation for this error utilizes the temporal difference between two FPAs that are substantially equally spectrally sensitive to the target substance. In such a case, the temporal difference image will highlight those pixels whose intensity has changed over time (rather than over wavelength). Thus, subtracting the data corresponding to these pixels on two FPAs that are substantially equally spectrally sensitive to the target substance to form the resulting image excludes the contribution of the target substance to the resulting image. Thus, the following distinction may occur: (i) scene changes caused by the presence of the target substance and (ii) scene changes caused by background changes unassociated with the target substance. In some embodiments, these two channels having the same or substantially similar spectral responses so as to be substantially equally spectrally sensitive to the target substance may include FPAs that operate using visible light. It should also be noted that data acquired using a visible light FPA (when present as part of an additional IR imaging system) can also be used to facilitate such discrimination and compensation of imaging errors caused by motion. Visible cameras typically have a much lower noise factor than IR cameras (at least during the day). Thus, the temporal difference image obtained using the image data from the visible light FPA can be very accurate. For example, as long as a moving object can be observed in the visible region of the spectrum, the visible FPA can be used to compensate for motion in the system and many potential false alarms in the scene due to motion caused by people, vehicles, birds, and steam. This has the additional benefit of providing an additional level of false alarm suppression without reducing the system sensitivity, since many targets such as gas clouds cannot be observed in the visible spectral region. In various embodiments, an IR camera can be used to compensate for motion artifacts.

[0147] Another method for detecting gases is to use a spectral unmixing scheme. The spectral unmixing scheme assumes that the spectrum measured at a detector pixel consists of a sum of component spectra (e.g., methane and other gases). This scheme attempts to estimate the relative weights of these components required to derive the measured spectrum. The component spectra are typically taken from a predefined spectral library (e.g., taken from an empirically assembled data set), but sometimes the scene can also be used to estimate these relative weights (commonly referred to as “endmember determination”). In various embodiments, the image obtained from a detector pixel is a radiance spectrum and provides information about the brightness of the object. To identify the content of a gas cloud in a scene and / or estimate the concentration of various gases in the gas cloud, the absorption / emission spectra of various gases of interest can be obtained by comparing the measured brightness with the estimated expected brightness. The spectral unmixing method can also benefit from time, parallax, and motion compensation techniques.

[0148] In various embodiments, a method for identifying the presence of a target substance in an object includes obtaining a radiation spectrum (or absorption spectrum) from the object in a spectral region indicating the presence of the target substance and calculating a correlation (e.g., a correlation coefficient) by correlating the obtained radiation spectrum (or absorption spectrum) with a reference spectrum of the target substance. The presence or absence of the target substance can be determined based on the correlation amount (e.g., the value of the correlation coefficient). For example, if the value of the correlation amount or correlation coefficient is greater than a threshold value, the presence of the target substance in the object can be confirmed. In various embodiments, the radiation spectrum (or absorption spectrum) can be obtained by obtaining a spectral difference image between a filtered optical channel and / or another filtered optical channel / unfiltered optical channel, or any combination thereof.

[0149] For example, an embodiment of a system configured to detect the presence of methane in a gas cloud includes optical components such that one or more of a plurality of optical channels is configured to collect IR radiation to provide spectral data corresponding to discrete spectral bands located within a wavelength range between about 7.9 μm and about 8.4 μm, corresponding to an absorption peak for methane. The multispectral data obtained in one or more optical channels can be correlated with a predetermined absorption spectrum of methane within a wavelength range between about 7.9 μm and 8.4 μm. In various embodiments, the predetermined absorption spectrum of methane can be stored in a database or reference library accessible to the system. Based on the amount of correlation (e.g., the value of the correlation coefficient), the presence or absence of methane in the gas cloud can be detected.

[0150] Examples of actual embodiments and operations

[0151] The embodiment 300 of FIG3 is configured to employ 12 optical channels and 12 corresponding microbolometer FPAs 336 to capture a video sequence substantially immediately after performing a calibration measurement. The video sequence corresponds to an image of a standard laboratory scene, and the calibration measurement is performed using a reference source comprising two shutters, as discussed above, one at room temperature and the other at 5°C above room temperature. Using 12 FPAs increases the chances of simultaneously detecting and estimating the concentrations of approximately 8 or 9 gases present in the scene. In various embodiments, the number of FPAs 336 can vary depending on the balance between operational requirements and cost considerations.

[0152] Due to the specific circumstances of operation in the IR range of the spectrum, the so-called noise equivalent temperature difference (or NETD) is preferably used and is similar to the SNR commonly used in visible spectrum instruments. The array of microbolometers FPA 336 is characterized by performing at NETD ≤ 72 mK at an f-number of 1.2. Each measurement is performed by summing four consecutive frames, and the reduction in the NETD value expected due to this summation will be given by the corresponding factor = 2. Therefore, under ideal measurement conditions, the FPA NETD should be about 36 mK.

[0153] It is noteworthy that the use of optically filtered FPAs in various embodiments of the systems described herein can provide systems with a greater number of pixels. For example, embodiments comprising a single large-format microbolometer FPA array can provide a system with a large number of pixels. Various embodiments of the systems described herein can also provide high optical throughput for a relatively small number of optical channels. For example, the systems described herein can provide high optical throughput for a plurality of optical channels, for example, between 4 and 50 optical channels. By having a smaller number of optical channels (e.g., between 4 and 50 optical channels), the systems described herein have a wider spectral range, which allows the signals collected within each spectral range to have a greater integrated intensity.

[0154] The embodiments described herein have an advantage over various scanning-based hyperspectral systems configured for target material detection (e.g., gas cloud detection) in that they can resolve the entire spectrum in snapshot mode (e.g., during a single image frame acquisition by an FPA array). This feature enables the imaging system embodiments described herein to utilize compensation algorithms, such as the aforementioned parallax and motion compensation algorithms. In effect, because the imaging data required to implement these algorithms is collected simultaneously with the target material-related data, the compensation algorithms are executed on the target material-related data rather than on data acquired at another time interval. This rapid data collection thus improves the accuracy of the data compensation process. Furthermore, the frame rate of data acquisition is significantly higher. For example, the imaging system embodiments described herein can operate at video rates of approximately 5 Hz and higher. For example, the various embodiments described herein can operate at frame rates of approximately 5 Hz to approximately 60 Hz or 200 Hz. Consequently, users can identify wisps and swirls typical of gas mixtures in images without obscuring these dynamic image features and other artifacts caused by scene changes (whether spatial or spectral) during long-term measurements. In contrast, scanning-based imaging systems involve image data acquisition over a period of time exceeding the time of a single snapshot, and thus may blur target gas features in the image and inevitably reduce the detection sensitivity that would otherwise be achievable. This result contrasts with the embodiments of the imaging system described herein, which are able to detect local concentrations of gas without being smeared in areas of thinner gas concentrations. In addition, the higher frame rate also enables a faster response to gas leaks (when detecting such leaks is the goal). For example, an alarm can be triggered in a fraction of a second instead of several seconds.

[0155] To demonstrate the operation and gas detection capabilities of the imaging system described in this paper,Figure 3A Example 300 of the construction of a prototype and its use to detect a hydrocarbon gas cloud of propylene at a distance of approximately 10 feet. Figure 7 Video frames 1 through 12 are shown representing the gas cloud detection output 710 (viewed as a streak of light) in the sequence from t = 1 to t = 12. Images 1 through 12 are selected frames taken from a sequence of video data captured at a video rate of 15 frames per second. The detected propylene gas is shown as a streak of light 710 (highlighted in red) near the center of each image. The first image was taken before the gas was ejected from the gas-containing nozzle, and the last image represents the system output shortly after the nozzle has been closed.

[0156] The same prototype of the system can also demonstrate the above-described dynamic calibration improvement by imaging the scene around the system (laboratory) with a known temperature difference. The results of implementing the dynamic correction process are shown in Figure 8A and 8B where the curve labeled "obj" (or "A") represents the temperature estimate of the region identified in the scene. Figure 8A and 8B In each graph of Figure 8A the abscissa indicates the number of FPAs, and the ordinate corresponds to the temperature (expressed in °C). Thus, it is expected that any given curve will be a substantially flat line when all detector elements receive radiation data that, when interpreted as the temperature of an object, indicates the same temperature of the object sensed by all detector elements. The data corresponding to each of the multiple "obj" curves are taken from a stream of video frames (a total of 50 frames) that are separated from each other by approximately 0.5 seconds. Figure 3A The recorded "obj" curves shown in

[0157] Figure 8B indicate that the detector elements are inconsistent with respect to the temperature of the object, and the difference in the temperature of the object sensed by different detector elements is up to approximately 2.5 °C. In addition, all of the temperature estimates are drifting frame by frame from time to time. The curve labeled "ref" (or "C") corresponds to the detector's temperature estimate of the aperture 338 of Example 300 of Figure 3A The results of the radiation detection performed after each detector pixel has undergone the above-described dynamic calibration process are represented by the curve labeled "obj corr" (or "B"). Now, the difference in the estimated temperature of the object in the detector elements is reduced to approximately 0.5 °C (thus improving the original reading by at least a factor of 5).

[0158] Dynamic calibration element and reference

[0159] Figure 9A and 9B schematically illustrate different embodiments 900 and 905 of an imaging system that includes various temperature calibration elements to facilitate dynamic calibration of an FPA. The temperature calibration elements can include mirrors 975a, 975b (represented as M 1A , M 9A , etc.) and reference sources 972a and 972b. Embodiment 900 can be configured similarly to embodiment 300 and includes one or more front objective lenses, separate apertures, one or more spectral filters, an imaging lens array 928a, and an imaging element 936. In various embodiments, the imaging element 936 (e.g., a camera block) can include a camera array. In various embodiments, the camera array can include an optical FPA unit. The optical FPA unit can include a single FPA, an FPA array. In various embodiments, the camera array can include one or more detector arrays, represented as the detector arrays 1, 5, and 9 in Figure 9A and 9B . In various embodiments, the FOV of each of the detector arrays 1, 5, 9 can be divided into a central region and a peripheral region. Without loss of generality, the central region of the FOV of each of the detector arrays 1, 5, 9 can include the region where the FOVs of all the detector arrays 1, 5, 9 overlap. In the embodiment shown in Figure 9A , the reference sources 972a and 972b are placed at a certain distance from, for example, the detector arrays 1, 5, 9, and the mirrors 975a and 975b that image them onto the detector arrays are then placed at the location of the scene reference aperture (e.g., Figure 3A 's 338).

[0160] In Figure 9A, mirrors 975a and 975b are configured to reflect radiation from reference sources 972a and 972b (denoted as refA and refB). Mirrors 975a and 975b can be positioned away from the central FOV of detector arrays 1, 5, and 9 so that the central FOV is not blocked or obscured by the images of reference sources 972a and 972b. In various embodiments, the FOV of detector array 5 can be larger than the FOVs of detector arrays 1 and 9. In such embodiments, mirrors 975a and 975b can be positioned away from the central FOV of detector array 5 so that reference sources 972a and 972b are imaged by detector array 5. Mirrors 975a and 975b can include imaging optics having optical power to image reference sources 972a and 972b onto detector arrays 1 and 9. In this example, reference sources 972a and 972b can be arranged in the same plane as re-imaging lens 928a, however, reference sources 972a and 972b can be arranged in different planes or in different locations. For example, reference sources 972a and 972b can be arranged in a plane conjugate to the plane in which detector arrays 1, 5, and 9 are arranged, such that focused images of reference sources 972a and 972b are formed by the detector arrays. In some embodiments, reference sources 972a and 972b can be arranged in a plane spaced apart from the conjugate plane, such that defocused images of reference sources 972a and 972b are formed by the detector arrays. In various embodiments, reference sources 972a and 972b need not be arranged in the same plane.

[0161] As discussed above, in some embodiments, reference sources 972a and 972b are imaged onto detector arrays 1 and 9 without much blurring, such that reference sources 972a and 972b are in focus. In contrast, in other embodiments, the images of reference sources 972a and 972b formed on detector arrays 1 and 9 are blurred, such that reference sources 972a and 972b are out of focus, thereby providing some averaging, smoothing, and / or low-pass filtering. Reference sources 972a and 972b may include surfaces of known temperature and may or may not include heaters or coolers attached thereto or in thermal communication therewith. For example, reference sources 972a and 972b may include a heater and a cooler, respectively, or may include a surface with a temperature sensor and heaters and sensors in direct thermal communication therewith, respectively, to control the temperature of the reference surface. In various embodiments, reference sources 972a and 972b may include thermostats configured to maintain reference sources 972a and 972b at a known temperature. In some embodiments, reference sources 972a and 972b may be associated with one or more sensors that measure the temperature of reference sources 972a and 972b and transmit the measured temperature to the thermostat. In some embodiments, one or more sensors may transmit the measured temperature to a data processing unit. In various embodiments, reference sources 972a and 972b may include surfaces of unknown temperature. For example, the reference source may include the wall of the housing containing the imaging system. In some embodiments, reference sources 972a and 972b may include surfaces that do not need to be associated with sensors or thermostats. However, in other embodiments, reference sources 972a and 972b may include surfaces that can be associated with sensors or thermostats.

[0162] In Figure 9B it, the temperature calibration elements include temperature control elements 972a and 972b (e.g., thermal control emitters, heating tapes, heaters, or coolers) disposed at a distance from detector arrays 1, 5, 9. In various embodiments, temperature control elements 972a and 972b may be disposed away from the central FOV of detector arrays 1, 5, 9 such that the central FOV is not blocked or occluded by the images of reference sources 972a and 972b. The radiation emitted from reference sources 972a and 972b is also imaged by detector array 936 together with the radiation incident from the object. Depending on the position of reference sources 972a and 972b, the images obtained by the detector arrays of the reference sources may be blurred (or out of focus) or sharpened (or in focus). The images 980a, 980b, 980c, 980d, 980e, and 980f of temperature control elements 972a and 972b may be used as references for calibrating one or more of the cameras in the dynamic calibration camera array.

[0163] In Figure 9A and 9BIn the depicted embodiment, detector arrays 1, 5, and 9 are configured to view (or image) reference sources 972a and 972b. Consequently, multiple frames (e.g., each frame or substantially each frame) within an image sequence contain one or more regions in the image where the object image has known thermal and spectral properties. This allows calibration of multiple (e.g., most or each) cameras within the camera array to be consistent with other (e.g., most or each) other cameras imaging the same reference source(s) or surface(s). For example, detector arrays 1 and 9 can be calibrated to be consistent with each other. As another example, detector arrays 1, 5, and 9 can be calibrated to be consistent with each other. In various embodiments, lens 928a provides blurred (or defocused) images of reference sources 972a and 972b on detector arrays 1 and 9 because the locations of the reference sources are not entirely in the conjugate planes of detector arrays 1 and 9. Although lens 928a is described as providing blurred or defocused images, in various embodiments, the reference sources or surfaces are imaged on detector arrays 1, 5, and 9 without such blur or defocus, and instead are in-focus images. Furthermore, optical elements may be used, such as e.g. Figure 9A The mirrors shown in FIG. 5 are used to provide this focused image.

[0164] The temperatures of the reference sources 972b and 972a may be different. For example, the reference source 972a may be at a temperature T A , and the reference source 972b may be at a temperature greater than T A Low temperature T B A heater may be provided below the temperature control element 972a to maintain it at a temperature T A , and a cooler may be provided below the temperature control element 972b to maintain it at a temperature T B In various embodiments, Figure 9A and 9B The embodiment shown in can be configured to image a single reference source 972, rather than imaging two reference sources 972a and 972b maintained at different temperatures. It should be understood that a single reference source does not need to be thermally controlled. For example, in various embodiments, multiple detectors in a detector array can be configured to image the same surface of at least one calibration element whose thermal and spectral properties are unknown. In such an embodiment, one of the multiple detectors can be configured as a reference detector, and the radiation spectrum obtained by the reference detector can be used to estimate the surface temperature of at least one calibration element imaged by the multiple detectors. The remaining multiple detectors can be calibrated so that their temperature and / or spectral measurements are consistent with the reference detector. For example, detector arrays 1 and 9 can be calibrated to be consistent with each other. As another example, detector arrays 1, 5, and 9 can be calibrated to be consistent with each other.

[0165] Reference sources 972a and 972b can be coated with a material to make them behave essentially as black bodies (whose emission spectrum is known for any given temperature). If temperature sensors are used at the locations of each reference source, the temperature can be tracked at these locations. Thus, regions in each camera's image can be defined (e.g., on detector arrays 1 and 9) where objects have such known temperatures (and therefore spectra). A calibration process can thus be used so that most, if not every, camera operating in this manner operates consistently with most or every other camera for objects at the temperatures represented by the two sources. Calibrating an infrared camera using sources at two different temperatures is called "two-point" calibration and assumes that the measured signal at a given pixel is linearly related to the incident irradiance. Because this calibration can be performed over multiple, many, or even every frame of a sequence, it is referred to as "dynamic calibration."

[0166] An example of a dynamic calibration process is as follows. If a reference source or reference surface has temperature sensors, the temperature measurements obtained with these temperature sensors can be used to determine its expected emission spectrum. These temperature measurements are labeled T for the "reference temperatures" of sources / surfaces A, B, and C. A [R]、T B [R] and T C [R]. These temperature measurements can be used as scalar correction factors to apply to the entire image from a given camera, forcing it to be consistent with the reference temperature. Correcting the temperature estimate for a given pixel from T to T' can be done using a method similar to the following reference Figure 10A 、 10B , 10C. If a direct temperature sensor is not used, a camera can be used instead. This camera can be called a "reference camera". In this case, the same formula as provided in the following paragraph can be used, but where T A [R] and T B [R] represents the temperature of the reference sources / surfaces A and B as estimated by the reference camera. By applying the dynamic calibration correction formula, all other cameras are forced to match the temperature estimate of the reference camera.

[0167] exist Figure 9B In the configuration shown, reference sources 972a and 972b are positioned so that the image of the sources on the detector array is blurred. Figure 9A The configuration shown in is similar to Figure 4 , wherein the reference source is placed at an intermediate image plane (e.g., a conjugate image plane). In this configuration, the reference aperture array (similar to Figure 4The reference aperture 438a) therein will have an associated reference source array or reference surface such that the reference source or surface (e.g., each reference source or surface) is imaged onto a camera or detector array (such as FPAs 1, 5, 9). With this scheme, the reference source or surface image is in the conjugate image plane and thus is not significantly blurred, such that their images can be made to block a smaller portion of each camera's field of view.

[0168] "Static" calibration (where the scene is largely blocked by a reference source such as Figure 9A and 9B the moving shutter 960 in [reference], such that imaging of the unknown scene cannot be performed in parallel with calibration) allows multiple cameras (e.g., most or each camera) to accurately estimate the temperature of multiple elements (e.g., most or each element in the scene) immediately after calibration is completed. However, it cannot prevent the estimates of the cameras from drifting relative to each other during the process of presenting the unknown scene. Dynamic calibration can be used to reduce or prevent such drift, such that all cameras imaging the scene may be forced to agree on the temperature estimate of the reference source / surface and adjust this correction during each frame.

[0169] Figure 10A FIG. schematically illustrates an exemplary imaging system 1000, in which one or more mirrors M 0A ... M 11A and M 0B ... M 11B are placed within the fields of view of one or more cameras 0,..., 11, partially blocking the fields of view. Cameras 0,..., 11 are arranged to form an outer ring of cameras, including cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4 that surround central cameras 5 and 6. In various embodiments, the FOVs of central cameras 5 and 6 may be less than or equal to the FOVs of the outer ring cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4. In such embodiments, one or more mirrors M 0A ... M 11A and M 0B ... M 11B may be placed outside the central FOVs of cameras 5 and 6 and in the peripheral FOVs of the camera outer ring of cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4 that do not overlap with the central FOVs of cameras 5 and 6, such that reference sources A and B are not imaged by cameras 5 and 6. In various embodiments, the FOVs of central cameras 5 and 6 may be greater than the FOVs of the outer ring cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4. In such embodiments, one or more mirrors M 0A ... M 11A and M 0B ... M 11BIt can be placed in the peripheral FOVs of cameras 5 and 6 that do overlap with the central FOVs of outer ring cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4, such that reference sources A and B are imaged by cameras 5 and 6.

[0170] This design is an enhancement of Figure 3A and 4 the systems 300 and 400 shown in. In the system 1000 shown in Figure 10A an array of two or more imaging elements (e.g., curved mirrors) is mounted at a certain distance from the FPA, e.g., in the plane of the reference aperture 160 shown in Figure 3A . These elements (mirrors or imaging elements) are used to image one or more temperature-controlled reference sources A and B onto the detector elements of two or more cameras. The main difference between embodiment 1000 and embodiments 300 or 400 is that now multiple or most or all of the outer ring cameras in the array can image both reference sources A and B, rather than imaging only one of the two reference sources A and B. Thus, most or all of the outer ring cameras image the same reference source or the same set of reference sources (e.g., both reference sources A and B), rather than using different reference sources for different cameras or imaging different parts of the reference sources as shown in Figure 3A and Figure 4 . Therefore, this scheme improves the robustness of calibration because it eliminates potential failures and errors due to having additional temperature sensors for estimating each reference source.

[0171] The imaging elements in system 1000 (shown as mirrors in Figure 10A and 10B ) image the surface of one or more temperature-controlled reference sources or calibration elements (shown as A and B in Figure 10A and 10B ) into the blocked region of the camera field of view. Figure 10B An example is shown where mirror M 0A images source / surface A onto camera 0, and mirror M 0BThe reference source / surface B is imaged onto camera 0, and the same applies to cameras 1, 2, and 3. In this way, each mirror is used to image the reference source / surface onto the detector array of the camera, such that many, most, or each frame within the image sequence contains one or more regions in the image where the object image has known thermal and spectral properties. This scheme allows calibration of most, if not each, of the cameras within the camera array to be consistent with most or each of the other cameras that image the same one or more reference sources. For example, cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4 can be calibrated to be consistent with each other. As another example, cameras 0, 1, 2, and 3 can be calibrated to be consistent with each other. As yet another example, cameras 0, 1, 2, 3, 7, 11, 10, 9, 8, 4, 5, and 6 can be calibrated to be consistent with each other. Thus, in various embodiments, two, three, four, five, six, seven, eight, nine, ten, eleven, or twelve cameras can be calibrated to be consistent with each other. However, in some embodiments, not all cameras are calibrated to be consistent with each other. For example, one, two, or more cameras may not be calibrated to be consistent with each other, but other cameras can be calibrated to be consistent with each other. In various embodiments, these mirrors can be configured to image reference sources / surfaces A and B onto different respective pixels of a given FPA. Without loss of generality, Figure 10A and 10B represent Figure 9A a top view of the embodiment shown in

[0172] Figure 10C Schematically illustrates a related embodiment 1050 of the imaging system, where one or more reference sources R 0A 、...、R 11A and R 0B 、...、R 11B are arranged around the array of detectors 0、...、11. In various embodiments, one or more reference sources R 0A 、...、R 11A and R 0B 、...、R 11B can be a single reference source imaged by detectors 0、...、11. In various embodiments, the central detector arrays 5 and 6 can have a FOV that is equal to or less than the FOV of the outer ring detectors 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4. In such an embodiment, the reference sources R 0A 、...、R 11A can be set away from the central FOV of the detector arrays 5 and 6 such that the light from the reference sources R 0A 、...、R 11AThe radiation of the reference source R is imaged only by the outer ring detectors 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4. In various embodiments, the central detector arrays 5 and 6 can have a FOV that is larger than the FOV of the outer ring detectors 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4. In such embodiments, the reference source R 0A ,...,R 11A can be arranged in the peripheral FOV of the detector arrays 5 and 6 so that the 0A ,...,R 11A The radiation from the reference source R is imaged only by the outer ring detectors 0, 1, 2, 3, 7, 11, 10, 9, 8, and 4. 0A ,...,R 11A The radiation of is imaged by the outer ring detectors 0, 1, 2, 3, 7, 11, 10, 9, 8 and 4 and the central cameras 5 and 6. Without loss of generality, Figure 10C express Figure 9B Top view of the embodiment shown in .

[0173] In various embodiments, a heater may be positioned below, adjacent to, or in thermal communication with the reference source / surface A to provide it with a higher temperature T A , and the cooler can be arranged below, adjacent to, or in thermal communication with the reference source B to make it have a lower temperature T B In various embodiments, Figure 10A 、 10B The embodiments shown in FIG. 10 and FIG. 10C can be configured to image a single reference source A rather than two reference sources A and B maintained at different temperatures. As discussed above, Figure 10A 、 10BThe embodiments shown in FIG10C and FIG10C can be configured to image the same surface of the calibration element. In such embodiments, the surface temperature of the calibration element need not be known. Many, most, or each reference source / surface can be coated with a material to cause it to behave substantially like a blackbody, whose emission spectrum for any given temperature is known. If many, most, or each camera in the camera array images both references A and B, such that there is a known region in the camera's image where the object has a known temperature (and therefore a known spectrum), a calibration process can be performed. This process can cause many, most, or each camera so operated to be consistent with various, most, or each other camera for the object at the temperature represented by the two sources. For example, two, three, four, five, six, seven, eight, nine, ten, eleven, or twelve cameras can be calibrated to be consistent with each other. However, in some embodiments, not all cameras are calibrated to be consistent with each other. For example, one, two, or more cameras may not be calibrated to be consistent with each other, but other cameras may be calibrated to be consistent with each other. As discussed above, calibration of an infrared camera using sources at two different temperatures is called a "two-point" calibration and assumes that the measured signal at a given pixel is linearly related to the incident irradiance.

[0174] Dynamic calibration is used to obtain the corrected temperature T' from the initial temperature T estimated at each pixel in the camera using the following formula:

[0175] T'[x,y,c]=(T[x,y,c]-T A [R])G[c]+T A [R]

[0176] Among them, T A [R] is the dynamic offset correction factor, and is the dynamic gain correction factor. The term c discussed above is the camera index identifying the camera whose data is being corrected.

[0177] III. Example of mobile DAISI system

[0178] According to some embodiments, the DAISI systems disclosed herein can be configured for long-term installation at a suitable location. For example, the DAISI system disclosed in Part II above can be fixed to a fixture on the ground installed at the location to continuously or periodically monitor the presence of gases or chemicals at the location. In some embodiments, for example, the DAISI system can be attached to a pole, post, or any suitable fixture at the location to be monitored. In such an arrangement, the DAISI system can continuously or periodically capture multi-spectral, multiplexed image data of the scene, and an on-board or remote computing unit can process the captured image data to identify or characterize the gases or chemicals at the location. A communication module can transmit data related to the identified gases or chemicals to any suitable external system, such as a central computing server, etc. For such long-term installation of the DAISI system, the installation site can include a power source (e.g., a power transmission line connected to a junction box at the site) and network communication equipment (e.g., network cabling, routers, etc.) to provide network communication between the DAISI system and the external system.

[0179] It may be advantageous to provide a mobile DAISI system configured to be worn or carried by a user. For example, it may be inappropriate or undesirable to install a DAISI system at some locations for a long time. As an example, some oil well sites may not have sufficient infrastructure (such as power or network communication equipment) to support the DAISI system. In addition, moving the DAISI system from one site to another to monitor different locations can be challenging. For example, when the system is connected to the infrastructure at the site to be monitored, installing and removing the DAISI system from the site for transportation may involve a significant amount of work and time for the user. Therefore, it may be desirable to provide a DAISI system that can be used independently of the facilities or infrastructure of the site to be monitored. Additionally, it may be advantageous to implement the DAISI system in a form factor and with a weight that can be carried or worn by a user. For example, the mobile DAISI system can enable the user to easily transport the system from one site to another while monitoring the presence of gases or chemicals in real time.

[0180] It should be recognized that each of the systems disclosed herein can be used to monitor potential gas leaks in any suitable installation site, including but not limited to drilling platforms, refineries, pipelines, transportation systems, ships or other vessels (such as offshore oil drilling platforms, trains, tank trucks, petrochemical plants, chemical plants, etc.). In addition, such as the above example regarding Figures 1 - 10C Each embodiment and aspect disclosed and illustrated herein can be used in combination with each of the embodiments Figures 11A - 14C disclosed and illustrated herein.

[0181] Figure 11A FIG. is a schematic illustration of a mobile infrared imaging system 1000 (e.g., a mobile or portable DAISI system) configured to be carried or worn by a human user 1275. When the user 1275 travels to a site to be monitored (such as an oil well site, a refinery, etc.), the user 1275 may wear a hat or helmet 1200. Figure 11A The system 1000 shown in FIG. is attached to the helmet 1200 by a support 1204, which securely mounts the system 1000 to the helmet 1200. For example, the support 1204 may include fasteners, straps, or any other suitable structure. Advantageously, mounting the system 1000 to the helmet 1200 enables the user 1275 to capture images within the field of view (FOV) of the system by turning his head to face a particular location to be monitored. For example, the user 1275 may walk through the site and may capture video images of each part of the site (e.g., various structures that may be vulnerable to gas or chemical leaks, such as valves, fittings, etc.). Thus, in the embodiment shown in Figure 11A the user 1275 may image each part of the site by facing the area to be imaged and ensuring that the system 1000 is activated. Additionally, by mounting the system 1000 to the user's helmet 1200, the user 1275 may use his hands for other tasks while the system 1000 images the site. Although Figure 11A the system 1000 is shown mounted to the user's helmet 1200, it should be appreciated that the system 1000 may alternatively be worn on other parts of the user's clothing or may be carried by the user, for example, in a bag, case, or other suitable container. Additionally, in some embodiments, a wind sensor may be provided to the user, for example, on the user's clothing and / or on or near the system 1000. The wind sensor may be used to estimate the wind conditions at the mounting site, which may be used to improve the detection of gas leaks. In other embodiments, the system 1000 may be coupled to or formed with a housing that defines a "gun" - like structure that may be aimed or pointed by the user in a particular direction.

[0182] As explained herein, the gas cloud 1202 emitted from a structure at a site can be imaged by pointing the system 1000 at the gas cloud 1202 and capturing an image of the gas cloud 1202 when the cloud 1202 is within the FOV of the system 1000. Different from other systems, the system 1000 can utilize a single snapshot to capture multi-spectral image data of a single scene at a series of IR wavelengths, as further explained in detail herein. A single snapshot can be captured within a short time frame, e.g., less than about 3 seconds, less than about 2 seconds, or less than about 1.5 seconds (e.g., in some embodiments, within about 1 second). A single snapshot can be captured within greater than about 5 milliseconds, greater than about 0.2 seconds, or greater than about 0.5 seconds. The captured image data can be processed by a processing unit on the system 1000, as further explained in detail herein. For example, the processing unit can process the image data from different optical channels and can compare the captured spectral information with a database of known chemicals to identify and / or characterize the gases contained in the gas cloud 1202.

[0183] A communication module onboard the system  1000 can send information related to the identified gas or chemical to any suitable external device. For example, the communication module can wirelessly (e.g., via Bluetooth, WiFi, etc.) transmit the information to a suitable mobile computing device, such as an electronic glasses device 1201, a tablet computing device 1212, a mobile smart phone, a laptop or notebook computer 1203, or any other suitable mobile computing device. In some embodiments, if a gas cloud is detected, the system 1000 can warn the user by sending a signal to a mobile device (e.g., a tablet computing device 1212 or a mobile smart phone). The mobile device can emit an audible ringtone and / or can vibrate to notify the user of a potential gas leak. In Figure 11A embodiments, the electronic glasses device 1201 can include a user interface that includes a display that the user 1275 can view in real time when he visits the site. In some embodiments, the electronic glasses device 1201 includes glasses that contain a display. The electronic glasses device 1201 can also be configured to present an image from the display to the wearer. The electronic glasses device 1201 can include, for example, projection optics that project an image onto the eye. The electronic glasses device 1201 can include head-mounted display optics that present an image on the lens portion(s) of the glasses such that the wearer can view the image and can also see through the glasses and gaze at distant objects. Other configurations are possible. In some arrangements, the glasses device 1201 can include a Google Glass device sold by Google Inc. of Mountain View, California.

[0184] The processing unit can configure the processed image data such that the type of the identified gas is displayed to the user 1275 on the display of the glasses device 1201. For example, in some embodiments, color-coded data can represent different types of gases or the concentration of a particular gas, and can be overlaid on the visible light image of the scene. For example, the user can see the color-coded data and the gas cloud image on the electronic glasses device 1201. In various embodiments, text data and statistical data regarding the composition of the gas cloud 1202 can also be displayed to the user 1275. Thus, the user 1275 can walk around the site and can view the different types of gases in the gas cloud 1202 substantially in real time. Advantageously, this real-time display of the composition of the gas cloud 1202 can enable the user 1275 to quickly report an emergency event, such as a leak of a toxic gas or chemical. In some embodiments, the detection of a toxic leak can trigger an alarm, which can cause emergency responders to assist in evacuating the site and / or fixing the leak.

[0185] In some embodiments, the processed image data can be sent from the system 1000 to the tablet computing device 1212, the laptop computer 1203, and / or the smart phone. The user 1275 can interact with the desktop computing device 1212 or the laptop computer 1203 to perform additional analysis on the imaging and the processed gas cloud 1202. Additionally, information regarding the gas cloud (including the processed data and / or the raw image data) can also be sent to a central server for centralized collection, processing, and analysis. In various arrangements, a Global Positioning System (GPS) module can also be installed on the system 1000 and / or on a mobile computing device (such as a tablet computing device, a smart phone, etc.). When a particular image is captured, the GPS module can identify the coordinates of the user 1275. The location data of the captured image data can be stored on the central server for further analysis.

[0186] Thus, Figure 11A the system 1000 shown in can enable the user 1275 to image multiple locations of a particular site to be monitored (such as an oil well site). Advantageously, the optical components, the processing components, and the communication components of the system 1000 can be integrated within a relatively small housing that can be carried or worn by the user 1275. For example, in various embodiments, the system 1000 does not include complex mechanical components for movement, such as gimbals, actuators, motors, etc. Without such components, the size of the system 1000 can be reduced relative to other systems.

[0187] Unlike other systems where the system components are large or assembled on a large form factor, the size and shape of the mobile system 1000 can be designed in a way that makes it easy to move and manipulate as the user 1275 moves around the site. In fact, integrating various system components into a small form factor can be quite challenging. Advantageously, the system 1000 can be worn or carried by a human user. For example, the components of the system 1000 can be collectively included in the data acquisition and processing module 1020, which can include a housing that supports the system components. The components of the system 1000 (including optical or imaging components, focal plane arrays, on-board processing electronics, and communication components) can be encapsulated or assembled in the data acquisition and processing module 1020 and can occupy a volume of less than about 300 cubic inches, less than about 200 cubic inches, or less than about 100 cubic inches. In various embodiments, the components of the system 1000 (including optical or imaging components, focal plane arrays, on-board processing electronics, and communication components) can be encapsulated or assembled in the data acquisition and processing module 1020 and can occupy a volume greater than about 2 cubic inches or greater than about 16 cubic inches.

[0188] The size and shape of the data acquisition and processing module 1020 (on or in which system components are installed) can be designed to fit within a box-shaped boundary having dimensions X x Y x Z. For example, the data acquisition and processing module 1020, which includes imaging optics, a focal plane array, and on-board processing electronics, can be included in a package whose size and shape are designed to fit within a box-shaped boundary having dimensions X x Y x Z. The package can also contain a power source, such as a battery and / or a solar module. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 8 inches x 6 inches x 6 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 7 inches x 5 inches x 5 inches, e.g., within a box-shaped boundary smaller than 7 inches x 3 inches x 3 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 6 inches x 4 inches x 4 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 2 inches x 2 inches x 6 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary having dimensions greater than 4 inches x 2 inches x 2 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary having dimensions greater than 3 inches x 3 inches x 7 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary having dimensions greater than 2 inches x 1 inch x 1 inch. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have dimensions smaller than 2 inches x 2 inches x 6 inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have dimensions greater than 1 inch x 1 inch x 3 inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have dimensions greater than 2 inches x 2 inches x 4 inches. The data acquisition and processing module has dimensions smaller than 6 inches x 3 inches x 3 inches.The data acquisition and processing module 1020 (including the imaging optics, focal plane array, and onboard processing electronics) may have dimensions of less than 4 inches x 3 inches x 3 inches. The data acquisition and processing module 1020 (including the imaging optics, focal plane array, and onboard processing electronics) may have dimensions of less than 3 inches x 2 inches x 2 inches. The data acquisition and processing module 1020 (including the imaging optics, focal plane array, and onboard processing electronics) may have dimensions of greater than 2 inches x 1 inch x 1 inch. The data acquisition and processing module 1020 (including the imaging optics, focal plane array, and onboard processing electronics) may have dimensions of greater than 1 inch x 0.5 inches x 0.5 inches. The data acquisition and processing module 1020 (including the imaging optics, focal plane array, and onboard processing electronics) may have a volume of less than 30 cubic inches. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) may have a volume of less than 20 cubic inches. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) may have a volume of less than 15 cubic inches. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) may have a volume of less than 10 cubic inches. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) may have a volume of greater than 1 cubic inch. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) may have a volume of greater than 4 cubic inches. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) may have a volume of greater than 5 cubic inches. The data acquisition and processing module 1020 (including imaging optics, focal plane array, and onboard processing electronics) can have a volume greater than 10 cubic inches. The package can also contain a power source (including batteries and / or solar modules), a communications module, or both, and fit within the dimensions described above. It should be appreciated that the dimensions disclosed herein may not correspond to . Figure 11A The directions shown in Figure 2 are for X, Y, and Z.

[0189] Additionally, the system 1000 may be of sufficiently low mass and weight to enable the user 1275 to easily carry or wear the data acquisition and processing module 1020 at the site. Figure 11A The size and shape of the embodiment shown in can be designed and configured to have qualities that enable a human user to easily and effectively manipulate the system 1000.

[0190] Figure 11Bis a schematic diagram illustrating an installation site (e.g., an oil well site, etc.) that may be monitored by multiple infrared imaging systems 1000 (e.g., DAISI systems). Figure 11B As shown, imaging system 1000A can be mounted to a pole 1309 or other fixed structure at the site. Imaging system 1000B can be worn or carried by multiple users 1275, imaging system 1000C can be mounted on a truck 1500, and / or imaging system 1000D can be mounted on an aerial platform 1501, such as an unmanned aerial vehicle (UAV) or a piloted aircraft. In some arrangements, the UAV can include an airplane, a helicopter (such as a quadcopter), etc. The embodiments disclosed herein can utilize image data captured by any combination of systems 1000A-1000D at an installation site to image the entire installation site in an efficient manner. In fact, each installation site can include any suitable number and type of systems 1000A-1000D. For example, each installation site may include more than two systems 1000A-1000D, more than five systems 1000A-1000D, more than ten systems 1000A-1000D, more than twenty systems 1000A-1000D. Each installation site may include fewer than about 100 systems 1000A-1000D.

[0191] For example, the central server can track the real-time location of each imaging system 1000A-1000D based on the GPS coordinates of the particular system or predetermined knowledge of the stationary location of the system. The distributed nature of the imaging systems 1000A-1000D can provide the central server with rich information about the type and location of gas leaks or other problems across multiple installation sites. Figure 11B A fixed system 1000A mounted to a fixed device, a portable system 1000B worn or carried by a person, a truck-based system 1000C, and an antenna-based system 1000D are illustrated, but it should be appreciated that other types of systems may be suitable. For example, in some embodiments, a robotic vehicle or walking robot can be used as a platform for the system 1000 disclosed herein. In various embodiments, a floating platform (such as a boat) can be used as a platform for the system 1000 disclosed herein. It should also be appreciated that the system disclosed herein can utilize any combination of platforms (e.g., a static fixed device such as a pole, (one or more) human users, (one or more) trucks or other vehicles, (one or more) aerial platforms, (one or more) floating platforms, (one or more) robotic platforms, etc.) to support the system 1000.

[0192] Figure 11B The system 1000 shown in FIG may include a mobile DAISI system similar to Figure 11AThe system shown in. In other embodiments, system 1000 may include a larger DAISI system configured for relatively long-term use. For example, Figure 11B The stationary imaging system 1000A shown in may be mounted on a pole 1309 or other suitable structure for monitoring a storage tank 1301. A solar panel 1300 may be provided at or near the system 1000 to assist in providing power to the system 1000. An antenna 1303 may be electrically coupled to the system and may provide wireless communication between the system 1000 and any other external entity, such as a central server, for storing and / or processing data captured by the system 1000.

[0193] If desired, a DAISI system such as system 1000 may be coupled to a unit that adjusts the translation, tilt, rotation, height, or other position of the system 1000. As an example, the system 1000 may be mounted to a translation and tilt unit. The translation and tilt unit may be capable of rotating the front portion of the system 1000 left and right (e.g., deflecting the system 1000 left and right) and capable of rotating the front portion of the system 1000 up and down (e.g., pitching the system 1000 up and down), thereby enabling the system 1000 to focus on a particular portion of the surrounding environment and, when desired, scan different regions of the surrounding environment (i.e., move through a desired scan path). The translation and tilt unit (or any other unit that adjusts the position of the system 1000) may include a motor, actuator, or other suitable mechanism to drive the movement of the system 1000. The operation of the translation and tilt unit (or any other unit that adjusts the position of the system 1000) may be controlled by the system 1000, by the translation and tilt unit, by a remote system, by a control system capable of controlling one or more systems 1000 and / or corresponding translation and tilt units, or by any suitable and desired control system.

[0194] The stationary infrared imaging system 1000A may be programmed to continuously or periodically monitor the site. If a gas cloud 1302 escapes from the storage tank 1301, such as by leaking from a ruptured valve, the system 1000A may capture multi-spectral, snapshot images or a series of images (e.g., a video stream) of the gas cloud 1302. As with Figure 11A the embodiments of, the imaging system 1000A may include imaging, processing, and communication components onboard the system 1000A to identify and characterize the type of gas in the cloud 1302 and send the processed data to a central server, for example, via the antenna 1303.

[0195] An imaging system 1000B worn or carried by multiple users 1275 can advantageously capture and process multispectral image data of portions of an installation site accessed by each user 1275. It should be recognized that different users 1275 can work or travel in different portions of the installation site (as well as multiple installation sites) over a period of time. When the imaging system 1000B worn or carried by the user 1275 is activated, it can continuously or periodically capture multispectral image data of different locations at the (one or more) installation sites the user 1275 travels to. As explained herein, the system 1000B can send the image data and the location where the image was captured to a central server. If the system 1000B or the central server detects a problem (such as a gas leak), the central server can associate the leak with a specific location and time.

[0196] Additionally, because the central server can receive image data and location data from multiple users at different locations and view from different perspectives, the central server can create an organization-wide map of gas leaks, which includes, for example, the location of gas leaks at any of the multiple installation sites, the type and concentration of each gas leaking, and the extent or degree, the specific user 1275 who captured the image data, and the time when the image was taken. Thus, each user 1275 carrying or wearing the portable imaging system 1000B can contribute information to the central server, which, when aggregated by the central server, provides rich details about the status of any gas leak at any installation site across the entire organization.

[0197] A vehicle-mounted imaging system 1000C can be installed in a truck or other type of vehicle (such as an automobile, van, all-terrain vehicle, etc.). As Figure 11BAs shown, the imaging system 1000C can be connected to one end of an extendable pole or extension member that is mounted to a truck 1500. The system 1000C can be raised and lowered via a control system to enable the system 1000C to image a wide area of the installation site. In some embodiments, actuators can be provided to change the angular orientation of the system 1000C, such as its pitch and yaw. A vibration isolation or reduction mechanism can also be provided to reduce vibrations that may interfere with the imaging process. The system 1000C can be battery-powered and / or can be powered by the truck; in some embodiments, a generator can be used to power the system 1000C. A user can drive the truck 1500 throughout the installation site to image various parts of the site to detect leaks. Additionally, the user can drive the truck 1500 to other installation sites to detect gas leaks. As explained herein, the location of the truck 1500 can be transmitted to a central server, and the location of the truck 1500 can be associated with each captured image. The truck 1500 can include GPS electronics to assist in tracking the location of the truck 1500 and / or the system 1000C over time as the user drives from one location to another. Similarly, an aerial platform 1501 (such as an unmanned aerial vehicle or UAV) can support the imaging system 1000D. The aerial platform 1501 can be (remotely or non-remotely) navigated to multiple installation sites to capture multispectral image data to detect gas clouds.

[0198] Accordingly, systems 1000A - 1000D can provide a wealth of data regarding the presence of leaks at multiple installations across an organization. Simultaneously or concurrently monitoring multiple cameras across an organization, site, region, or entire country can be achieved at least in part by providing wireless (or wired) communication between systems 1000A - 1000D and one or more central servers. Advantageously, collecting image data from multiple sources and multiple platforms can enable an organization to create a real - time map of potential gas leaks, the type and quantity of gas leaking, the location of the leak, and the time when the image data of the leak was captured. In some arrangements, the aggregation of data regarding a site can enhance the security of the installation site. For example, if a gas leak is detected at a particular installation, the embodiments disclosed herein can alert the appropriate staff, who can initiate safety and / or evacuation procedures. Additionally, the aggregation of data across an organization (such as an oil services company) can provide site - wide, region - wide, and / or company - wide performance metrics. For example, a given facility can monitor its total emissions over time and use the resulting data to help determine the overall performance of the facility. A given region (such as a metropolitan area, state, etc.) can monitor emission trends over time, thus providing values upon which decisions can be based. Similarly, a company can view the emission performance at all of its facilities and can decide whether certain facilities should receive new investments to improve performance, and / or whether the entire company should make various improvements. Accordingly, the mobile system 1000 disclosed herein can provide an omnipresent monitoring system for decision - making. Additionally, the system 1000 disclosed herein can be used in feedback control processes to improve various manufacturing processes based on the gases detected by the system(s) 1000. Accordingly, a control module can be provided to adjust manufacturing processes and / or parameters based on the gases measured by system 1000.

[0199] Embodiments of the mobile infrared imaging system 1000 disclosed herein offer various advantages over other systems. As described above, the aggregation of data regarding a site and its potential gas leaks can provide an organization - wide or system - wide map of potential problems. Additionally, the automatic detection of gas leaks (and the identification of the gas within the gas cloud) can simplify the operation of system 1000 and can reduce the risk of user error when attempting to manually detect or identify a gas cloud. Additionally, the small size of the system 1000 disclosed herein is easier for a user to carry or wear than other systems. Furthermore, the system 1000 disclosed herein can overlay the identified gas cloud on a visible image of the scene and can color - code the gas cloud based on, for example, gas type, concentration, etc.

[0200] Figure 12FIG. 0 is a schematic system block diagram showing a mobile infrared imaging system 1000 (e.g., a mobile DAISI system) according to one embodiment. The imaging system 1000 may include a data acquisition and processing module 1020 configured to be worn or carried by a person. The data acquisition and processing module 1020 may include, contain, or house an optical system 1015, a processing unit 1021, a power supply 1026, a communication module 1025, and a GPS module 1025. In other embodiments, the data acquisition and processing module 1020 may be configured to be mounted to a structure at a site to be monitored, such as a pole. A power supply unit 1026 may be provided on the system 1000. The power supply unit 1026 may be configured to supply power to various system components, such as the optical system 1015, the processing unit 1021, the communication module 1024, and / or the GPS module 1025. In some embodiments, the power supply unit 1026 may include one or more batteries (which may be rechargeable) to power the system components. In some embodiments, the power supply unit 1026 may include a solar system that includes one or more solar panels for powering the system with sunlight. In some embodiments, the power supply unit 1026 may include various power electronic circuits for converting AC power supplied by a standard power transmission line into DC power for powering the system components. Other types of power supplies may be suitable for the power supply unit 1026.

[0201] The system 1000 may include an optical system 1015 configured to capture multi-spectral image data in a single snapshot, as explained herein. The optical system 1015 may correspond to any suitable type of DAISI system, such as but not limited to the optical systems and devices shown above in Figures 1 - 10C and / or the optical system 1015 shown below in Figures 13A - 13B . For example, the optical system 1015 may include components and an optical focal plane array (FPA) unit that define at least two optical channels that are spatially and spectrally distinct from each other. The two optical channels may be positioned to transmit IR radiation incident on the optical system toward the optical FPA. Multiple channels may be used to multiplex different spectral images of the same scene and to image different spectral images on the FPA unit.

[0202] The processing unit 1021 can also be provided on the data acquisition and processing module 1020. The processing unit 1021 can include a processor 1023 and a memory 1022. The processor 1023 can operatively cooperate with the memory 1022, and the memory 1022 can contain computer-readable code which, when loaded onto the processor 1023, enables the processor 1023 to acquire multi-spectral optical data representing a target substance of a gas or chemical from the IR radiation received at the optical FPA unit of the optical system 1015. The memory 1022 can be any suitable type of memory (such as a non-transitory computer-readable medium) for storing data captured by the optical system 1015 and / or processed by the processing unit 1021. The memory 1022 can also store software executed on the processor 1023. The processor 1023 can be configured to execute software instructions for processing the multi-spectral image data captured by the optical system 1015. For example, the processor 1023 can analyze different images detected by the FPA and can compare the captured data with known signatures of various types of gases or chemicals. Based on the analysis of the captured image data, the processor can be programmed to determine the type and concentration of the gas in the gas cloud. Additionally, as explained herein, the processor 1023 can analyze the calibration data provided by the optical system 1015 to improve the accuracy of the measurement.

[0203] Advantageously, the processor 1023 can include one or more field programmable gate arrays (FPGAs) configured to execute methods used in analyzing the images captured by the optical system 1015. For example, the FPGA can include logic gates and read access memory (RAM) blocks designed to rapidly implement the calculations for detecting the gas type in the gas cloud. The small size / weight and high performance characteristics of the FPGA can enable on-board computing and analysis within the data acquisition and detection unit 1020 worn or carried by the user. Using the FPGA (or similar electronics) on-board the system 1000 can reduce the costs associated with performing image analysis calculations using off-site central servers or larger computing devices. Additionally, implementing the calculations with one or more FPGA devices on-board the wearable system can also prevent or reduce the communication bottlenecks associated with wirelessly transmitting large amounts of raw data from the system 1000 to a remote server or computer, which can be used in some embodiments.

[0204] The communication module 1024 may be configured to communicate with at least one device that is physically separate from the data acquisition and processing module 1020. For example, the communication module 1024 may include a wireless communication module configured to wirelessly communicate with at least one separate device. The wireless communication module may be configured to provide wireless communication via a wireless network (e.g., a WiFi Internet network, a Bluetooth network, etc.) and / or via a telecommunication network (e.g., a 3G network, a 4G network, etc.).

[0205] In some embodiments, for example, the wireless communication module can provide data communication between the data acquisition and processing module 1020 and a mobile device (such as an electronic eyewear device, a tablet computing device, a mobile smartphone, a laptop or notebook computer, or any other suitable mobile computing device). As explained herein, the mobile device can include a display on which the processed image data can be displayed to the user. For example, the type (and / or concentration) of the gas in the gas cloud can be shown on the display, for example, using color coding or other suitable graphical schemes. In some arrangements, the processed data can overlay a visible image of the scene. In some embodiments, the wireless communication module can provide data communication between the system 1000 and an external device (such as a central server) remote from the system 1000. For example, the processed image data and / or raw image data can be sent to the central server via a telecommunications network for storage and / or further analysis. In some embodiments, the processed image data or raw image data can be uploaded to a mobile device (e.g., a notebook computer, smartphone, tablet computing device, etc.), which can then transmit the image data to the central server.

[0206] The GPS module 1025 can be configured to determine the location of the data acquisition and processing module 1020 at a particular time. The processing unit 1021 can store the location data and, in some arrangements, can associate the location data with a particular image captured by the optical system 1015. In some arrangements, the location data associated with the captured image can be sent by the communication module 1024 (or by an external device) to a central server.

[0207] The optical system 1015, the processing unit 1021, the power supply 1026, the communication module 1024, and / or the GPS module 1025 may be included or housed within a data collection and processing module 1020 that can be carried or worn by a user. The components of system 1000 (including optical components, processing components, and communication components) may be encapsulated or assembled within the data collection and processing module 1020 and may occupy a volume less than about 300 cubic inches, less than about 200 cubic inches, or less than about 100 cubic inches. In various embodiments, the components of system 1000 (including optical components, processing components, and communication components) may be encapsulated or assembled within the data collection and processing module 1020 and may occupy a volume greater than about 2 cubic inches or greater than about 16 cubic inches. A power supply including a battery and / or a solar module may also be included among the components encapsulated or assembled within the data collection and processing module 1020 and is adapted to the above volume dimensions.

[0208] The size and shape of the data collection and processing module 1020, within or on which system components including imaging optics, a focal plane array, and on-board processing electronics are mounted, may be designed to fit within a box-shaped boundary having dimensions X x Y x Z. For example, in some embodiments, the size and shape of the data collection and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) may be designed to fit within a box-shaped boundary less than 8 inches x 6 inches x 6 inches. In some embodiments, the size and shape of the data collection and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) may be designed to fit within a box-shaped boundary less than 7 inches x 5 inches x 5 inches. In some embodiments, the size and shape of the data collection and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) may be designed to fit within a box-shaped boundary less than 6 inches x 4 inches x 4 inches. In some embodiments, the size and shape of the data collection and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) may be designed to fit within a box-shaped boundary having dimensions greater than 4 inches x 2 inches x 2 inches. In some embodiments, the size and shape of the data collection and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) may be designed to fit within a box-shaped boundary having dimensions greater than 2 inches x 1 inch x 1 inch. A power supply including a battery and / or a solar module, a communication module, or both may be included within the data collection and processing module 1020 and is adapted to the above dimensions. It should be recognized that the dimensions disclosed herein may not correspond to Figure 11AThe directions shown for X, Y, and Z. Additionally, system 1000 can have a mass and weight small enough so that user 1275 can easily carry or wear the data collection and processing module 1020 at the site.

[0209] Figure 13A is a schematic system diagram of an optical system 1015 configured for use in the mobile infrared imaging system 1000 disclosed herein. As explained herein, Figure 13A the optical system 1015 shown can be provided in the data collection and processing module 1020 worn or carried by a user. The optical system 1015 can be configured to capture multi - spectral image data of an object 1007, such as a gas cloud, chemical spill, etc. Figure 13A The components of the optical system 1015 shown can be similar or identical to the components of the optical systems and devices referenced herein Figures 1 - 10C described. The optical system 1015 can include a focal plane array (FPA) unit 1008, which is configured to record infrared image data captured by system 1000. As Figure 13A shown, the FPA unit 1008 can advantageously be uncooled, e.g., without a cooling system.

[0210] The optical system 1015 can include a front window 1006 through which light from the object 1007 passes. A first movable blackbody source 1003 and a second movable blackbody source 1004 can be provided to enable calibration of the optical system 1015. The movable sources 1003, 1004 can move in front of the field of view so that the optics image these sources for calibration. For example, the first blackbody source 1003 and the second blackbody source 1004 can be maintained at different known temperatures in a stable manner. For example, heaters and temperature sensors can be attached to each of the blackbody sources 1003, 1004 to provide feedback to create a stable and known temperature difference (e.g., at least 50 mK in some arrangements) between different spatial regions of the sources.

[0211] Furthermore, the optical system 1000 can include a dynamic calibration means for dynamically calibrating system 1000. As Figure 13A shown, one or more calibration sources 1009, 1010 can be provided. The calibration sources 1009, 1010 can include thermoelectric control (TEC) materials to which temperature sensors are attached. The calibration sources 1009, 1010 can be coated with a coating or paint for spectral measurement. Light from the calibration sources 1009, 1010 can be reflected from one or more mirrors 1005 and directed through a lens array 1002 (described below) to be imaged on a portion of the FPA unit 1008 to assist in dynamically calibrating system 1000 (e.g., while imaging an image of a target gas cloud).

[0212] The optical system 1000 may include a lens array 1002 to focus incoming light onto the FPA unit 1008. Figure 13A As shown, each lens of lens array 1002 can at least partially define or be included in an optical channel imaged by FPA unit 1008. To improve the mobility and portability of mobile imaging system 1000, lens array 1002 can include an integrated unit formed from or assembled into a single unitary body. Such an integrated lens array 1002 can reduce the size of imaging system 1015, and therefore the size of system 1000, at least in part to enable system 1000 to be worn or carried by a user. Lens array 1002 can be monolithically formed in any suitable manner. For example, in various embodiments, lens array 1002 can be formed using a diamond milling tool. In some embodiments, lens array 1002 can include a single piece of transparent material having individual regions shaped as curved refractive surfaces to create individual lenses. In some embodiments, lenses can be inserted into an array of openings formed in a plate or substrate to create lens array 1002.

[0213] The optical system 1000 may also include an infrared (IR) filter array 1001, which is configured to filter wavelengths of infrared light in an appropriate manner. Figures 5A - 6D Examples of IR filters and filtering techniques are disclosed. Figure 13A As shown, an IR filter 1001 can be disposed between the lens array 1002 and the FPA unit 1008. The IR filter 1001 can at least partially define a plurality of optical channels to be imaged by the FPA unit 1008. In some embodiments, the IR filter 1001 can be located between the lens array 1002 and the first movable blackbody source 1009 and the second movable blackbody source 1010.

[0214] Figure 13B is a schematic system diagram of optical system 1015 configured for use in mobile infrared imaging system 1000 disclosed herein in accordance with various embodiments. As explained herein, Figure 13B The optical system 1015 shown in FIG. 1 may be provided in a data acquisition and processing module 1020 worn or carried by a user. Figure 13B The components of the optical system 1015 shown in FIG. 1 may be similar to those described herein with respect to Figures 1 - 10C The components of the optical system and apparatus are similar or identical to those described in FIG13A.

[0215] Figure 13B The optical system 1015 may include an FPA unit 1408 configured to image an object 1409 such as a gas cloud or a chemical leak. Figure 13AAs in the embodiment shown, Figure 13B the system 1015 may include a front window 1406 (through which light from the object 1409 passes), a first movable blackbody source 1403 and a second movable blackbody source 1404, an IR filter array 1401, and a lens array 1402. As with Figure 13A the embodiment of, the lens array 1402 may include an integral or monolithic body. In Figure 13B the embodiment, the lens array 1402 may be disposed between the filter array 1401 and the FPA unit 1408. In other arrangements, the filter array 1401 may be disposed between the lens array 1402 and the FPA unit 1408.

[0216] Figure 13B the optical system 1015 may include a cooling unit 1430 configured to cool the FPA unit 1408. The cooling unit 1430 may include a cooling finger configured to cryogenically cool the FPA array 1408 in various arrangements. As Figure 13B shown, the filter array 1401, the lens array 1402, and the FPA unit 1408 may be disposed in a cooling region 1440. The blackbody sources 1403, 1404, and the front window 1406 may be disposed in a non-cooling region 1450. Setting the blackbody sources 1403, 1404 at a non-cooling temperature and setting the filter array 1401, the lens array 1402, and the FPA unit 1408 at a cooling temperature may facilitate the periodic calibration of the system 1000.

[0217] Figure 14A is a schematic perspective view of a mobile infrared imaging system 1000 (e.g., a mobile DAISI system) mounted to a helmet 1200 according to various embodiments. Figure 14B is Figure 14A an enlarged schematic perspective view of the mobile infrared imaging system 1000 shown in. The helmet 1200 may include a part of the user's personal protective equipment and may also advantageously serve as a platform for the imaging system 1000. As described above, when the user visits a particular installation site to be monitored (such as an oil well site, a refinery, etc.), the user may wear the helmet 1200. The system 1000 may be activated to continuously monitor and analyze the site visited by the user. Thus, the system 1000 may continuously and actively search for gas leaks anywhere the user visits and may initiate an alarm or other notification if a leak is detected.

[0218] In Figure 14B the embodiment shown, the imaging system 1000 may include a housing 1590, a data acquisition and processing module 1020 (see, for example, Figure 12and the associated description) is installed or coupled within or to the housing 1590. The support member 1592 can be coupled to or formed with the housing 1590 and can be configured to be attached to the helmet 1200 or any other suitable platform. For example, in some embodiments, the support member 1592 can include one or more mounting holes for attachment to the helmet 1200 by, for example, screws, bolts, or other fasteners. Additionally, as Figure 14B shown, the front window 1506 can be disposed at the front end of the housing 1590. The front window 1506 can be transparent to IR radiation and can at least partially define the aperture of the system 1000. In some embodiments, the window 1506 includes germanium. A diamond-like carbon coating (DLC) or other coating or layer can be provided on the window 1506 to provide a durable surface.

[0219] As explained herein, the system 1000 can be configured to be worn or carried by a human user. Thus, the data acquisition and processing module 1020 can be appropriately dimensioned such that the user can easily wear or carry the system 1000. For example, the data acquisition and processing module 1020 can be at least partially defined by the dimensions X x Y x Z, as Figure 14A and 14B shown.

[0220] Unlike other systems in which system components are bulky or assembled on large form factors, the size and shape of the mobile system 1000 can be designed in such a way that it is easily moved and manipulated as a user moves around the site. In practice, integrating the various system components in a small form factor can be very challenging. Advantageously, the system 1000 disclosed herein can be worn or carried by a human user. For example, the components of the system 1000 can be contained together in a data acquisition and processing module 1020, which can include a housing 1590 that supports the system components. The components of the system 1000 (including optical or imaging components, focal plane arrays, onboard processing electronics, and communication components) can be packaged or assembled in the data acquisition and processing module 1020 and can occupy a volume of less than about 300 cubic inches, less than about 200 cubic inches, or less than about 100 cubic inches. In various embodiments, the components of system 1000 (including optical or imaging components, focal plane array, onboard processing electronics, and communication components) can be packaged or assembled in data acquisition and processing module 1020 and can occupy a volume greater than about 2 cubic inches or greater than about 16 cubic inches. In some embodiments, the components of system 1000 (including optical or imaging components, focal plane array, onboard processing electronics, and communication components) can be packaged or assembled in data acquisition and processing module 1020 and can occupy a volume in the range of about 4 cubic inches to about 15 cubic inches. In some embodiments, the components of system 1000 (including optical or imaging components, focal plane array, onboard processing electronics, and communication components) can be packaged or assembled in data acquisition and processing module 1020 and can occupy a volume in the range of about 5 cubic inches to about 12 cubic inches. In some embodiments, the components of system 1000 (including optical or imaging components, focal plane array, onboard processing electronics, and communication components) can be packaged or assembled in data acquisition and processing module 1020 and can occupy a volume in the range of about 4 cubic inches to about 6.5 cubic inches, such as about 5.63 cubic inches in one embodiment. In some embodiments, the components of system 1000 (including optical or imaging components, focal plane array, onboard processing electronics, and communication components) can be packaged or assembled in data acquisition and processing module 1020 and can occupy a volume in the range of about 9 cubic inches to about 13 cubic inches, such as about 11.25 cubic inches in one embodiment. In some embodiments, the components of system 1000 (including optical or imaging components, focal plane array, onboard processing electronics, and communication components) can be packaged or assembled in data acquisition and processing module 1020 and can occupy a volume in the range of about 6 cubic inches to about 10 cubic inches.

[0221] The size and shape of the data acquisition and processing module 1020 (on which or in which system components are installed) can be designed to fit within a box-shaped boundary having dimensions X x Y x Z. For example, the data acquisition and processing module 1020, which includes imaging optics, a focal plane array, and on-board processing electronics, can be included in a package whose size and shape are designed to fit within a box-shaped boundary having dimensions X x Y x Z. The package can also contain a power source, such as a battery and / or a solar module. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 8 inches x 6 inches x 6 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 7 inches x 5 inches x 5 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 6 inches x 4 inches x 4 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary smaller than 6 inches x 2 inches x 2 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary having dimensions greater than 4 inches x 2 inches x 2 inches. In some embodiments, the size and shape of the data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can be designed to fit within a box-shaped boundary having dimensions greater than 2 inches x 1 inch x 1 inch. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have dimensions smaller than 3 inches x 2 inches x 2 inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have dimensions greater than 1 inch x 0.5 inch x 0.5 inch. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume smaller than 30 cubic inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume smaller than 20 cubic inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume smaller than 15 cubic inches.The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume of less than 10 cubic inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume greater than 1 cubic inch. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume greater than 4 cubic inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume greater than 5 cubic inches. The data acquisition and processing module 1020 (including imaging optics, a focal plane array, and on-board processing electronics) can have a volume greater than 10 cubic inches. The package can also include a power source (including a battery and / or a solar module), a communication module, or both, and is adapted to the above dimensions. It should be recognized that the dimensions disclosed herein may not correspond to. Figure 11A the directions shown for X, Y, and Z in. The package can also include a power source (including a battery and / or a solar module), a communication module, or both, and is adapted to the above dimensions. It should be recognized that the dimensions disclosed herein may not correspond to Figure 11A the directions shown for X, Y, and Z in.

[0222] In some embodiments, Figure 14B the dimension X shown in can be in the range of about 2 inches to about 7 inches, or more specifically, in the range of about 2 inches to about 4 inches, for example, about 2.5 inches in one embodiment. In some embodiments, Figure 14B the dimension X shown in can be in the range of about 4 inches to about 6 inches, for example, about 5 inches in one embodiment. In some embodiments, Figure 14B the dimension Y shown in can be in the range of about 1 inch to about 5 inches, or more specifically, in the range of about 1 inch to about 3 inches, for example, about 1.5 inches in one embodiment. In some embodiments, Figure 14B the dimension Z shown in can be in the range of about 1 inch to about 5 inches, or more specifically, in the range of about 1 inch to about 3 inches, for example, about 1.5 inches in one embodiment.

[0223] Additionally, system 1000 can have a mass and weight small enough for user 1275 to easily carry or wear the data collection and processing module 1020 at a site. For example, the weight of system 1000 can be in the range of about 0.5 pounds to 5 pounds, or more specifically, in the range of about 0.5 pounds to 2 pounds, or more specifically, in the range of about 0.25 pounds to about 2 pounds, or more specifically, in the range of about 0.25 pounds to about 1.5 pounds. In one embodiment, for example, system 1000 can weigh about 1 pound. In another embodiment, for example, system 1000 can weigh about 0.5 pounds. Thus, Figure 11A the dimensions and shape of the embodiment shown in Figure 11A can be designed and configured to have a mass that enables a human user to easily and effectively manipulate system 1000.

[0224] Figure 14C is Figure 14A - 14B a perspective cross-sectional view of the mobile infrared imaging system 1000 shown in Figure 14A - 14B . The mobile infrared imaging system 1000 can include one or more movable shutters 1503 (e.g., two shutters) behind window 1506 and a lens assembly 1502 behind the (one or more) shutters 1503. A filter array 1501 can be disposed behind (or in front of) the second lens array 1502B, and an optical focal plane array (FPA) unit 1508 can be disposed behind the filter array 1501. The optical FPA unit 1508 can be mechanically and electrically coupled to one or more substrates 1586, which can include a printed circuit board or PCB substrate. In various embodiments, the FPA unit 1508 includes a single FPA or detector array. Additionally, as explained herein, the lens assembly 1502, the filter array 1501, and the optical FPA unit can at least partially define one or more optical channels that are spatially and spectrally distinct. The number of optical channels can be at least 4, at least 5, at least 8, at least 9, at least 12, at least 13, or at least 20. In some embodiments, the number of optical channels is between 4 and 50.

[0225] One or more batteries 1588 can power system 1000 through the (one or more) substrates 1586. Additionally, a visible light imaging sensor 1580 can be disposed in housing 1590 and can be configured to provide a visible light image of the scene being captured by system 1000. The processed IR image data can be overlaid on the visible light image. In various embodiments, the visible light imaging sensor 1580 can be used to reduce detection errors caused by scene motion, e.g., detecting moving objects (such as animals or people) entering the field of view and that would interfere with the data being collected.

[0226] As explained herein, the (one or more) movable shutters 1503 can be configured to provide spectral radiometric calibration to the system 1000. The (one or more) shutters 1503 can be configured to move into and out of the field of view of the lens assembly 1502 periodically, e.g., in a range of about 1 minute to about 15 minutes, or more specifically, in a range of about 3 minutes to about 7 minutes, e.g., for a period of about 5 minutes. Although one shutter 1503 is illustrated in Figure 14C , it should be recognized that two or more shutters can be provided. The (one or more) shutters 1503 can be used in a static calibration process to provide an absolute temperature value to the system. In some embodiments, only static calibration is performed, e.g., no dynamic calibration is performed. In some embodiments, both a static calibration process and a dynamic calibration process are performed.

[0227] The lens assembly 1502 can include a first lens array 1502A and a second lens array 1502B. In some embodiments, the lens assembly 1502 can include an array of two-part lenses represented by the first array 1502A and the second array 1502B. In some embodiments, the lens assembly 1502 can include an array of two separate lenses represented by the first array 1502A and the second array 1502B. Each of the lens arrays 1502A, 1502B can include a 4x3 lens array, and each lens array can correspond to a specific detector region in the FPA unit 1508 and can define an optical channel of the system 1000. The lenses used in the first lens array 1502A can be different from the lenses used in the second lens array 1502B. The lenses can be of any suitable type, including, for example, spherical lenses, aspherical lenses, rod lenses, etc. or any combination thereof. For example, the lenses used in the first lens array 1502A can include aspherical lenses, and the lenses used in the second lens array 1502B can include rod lenses. Although Figure 14C the lens assembly 1502 shown therein includes two lens arrays, it should be recognized that additional lens arrays can be used, e.g., three lens arrays, four lens arrays, five lens arrays, etc. Additionally, to assist in achieving a small system size, the diameter of each lens in the assembly 1502 can be less than about 0.5", e.g., in a range of about 0.1" to about 0.5". The f-value of each lens can be less than about 2, e.g., in a range of about 0.2 to 2, or more specifically, in a range of about 0.5 to 2, or 1.0 to 2, or 1.1 to 2.

[0228] The first lens array 1502A and the second lens array 1502B can be coupled to each other by a mounting plate 1584, and the size and shape of the mounting plate 1584 are designed to support or receive each lens array 1502A, 1502B. For example, the first lens array 1502A can be mounted on one side of the mounting plate 1584, and the second lens array 1502B can be mounted on the opposite side of the mounting plate 1584. The mounting plate 1584 can be machined to have a diameter tolerance of approximately + / -25 micrometers. The lenses of the arrays 1502A, 1502B can be fixed to the mounting plate 1584 with a curable epoxy resin. For example, the lenses can be assembled in the opposite sides of holes formed in the mounting plate 1584.

[0229] The optical FPA unit 1508 may include any suitable type of detector array configured to detect infrared radiation having a wavelength, for example, greater than 1 micron, or greater than 2 microns, or greater than 3 microns or greater than 5 microns, or greater than 6 microns and possibly less than 20 microns, or 15 microns, or 13 microns, or 12 microns or 10 microns, and may be cooled or uncooled. In some embodiments, the optical FPA unit 1508 includes one or more microbolometer arrays, which may be uncooled. For example, an array of approximately 1000x1000 microbolometers may be used in the embodiments disclosed herein. Microbolometer arrays such as those manufactured by DRS Technologies of Arlington, Virginia, and Sofradir EC, Inc. of Fairfield, New Jersey, are suitable for the embodiments disclosed herein. For example, in some embodiments, the DRS U8000 FPA manufactured by DRS Technologies may be used. In some arrangements, the microbolometer array may have a resolution of 1024x768, with a pixel pitch of 12 microns. The lens array may form separate channels having an image detection region that forms part of the array. For example, in a 1024x768 pixel array on the detector array (microbolometer array), there may be 12 channels, and for each of the 12 channels, there are, for example, 250x250 pixels. Detector arrays with more or fewer pixels may be employed. Similarly, the number of channels may be greater than or less than 12, and the detection region on the detector array for a single channel may be greater than or less than 250x250 pixels. For example, the detection region may include between 100 - 200 pixels x 100 - 200 pixels per detection region. For example, the detection region may include 100 - 200 pixels x 100 - 200 pixels per detection region, 200 - 300 pixels x 200 - 300 pixels per detection region, or 300 - 400 pixels x 300 - 400 pixels, or 400 - 500 pixels x 400 - 500 pixels. Similarly, the detection region of the channels may measure 100 - 200 pixels on one side, 200 - 300 pixels on one side, 300 - 400 pixels on one side, 400 - 500 pixels on one side or larger or smaller.

[0230] In some arrangements, the spectral band of the microbolometer can be from about 7.5 microns to 14 microns, or can be from about 3 microns to 14 microns or 3 to 8 microns. The microbolometer array can operate at a frame rate of about 30 Hz and can operate at an operating temperature from about -40 °C to +70 °C. In various embodiments, the microbolometer array is an uncooled microbolometer that does not include a cooler. The sensitivity of the microbolometer at F / 1 can be < about 40 mK. The system 1000 disclosed herein can be used to detect wavelengths in the range from about 1 micron to about 20 microns. For example, the system 1000 disclosed herein can be used to detect wavelengths above about 6 microns, such as, in the range from about 6 microns to about 18 microns, in the range from about 3 microns to about 14 microns, or more specifically, in the range from about 7 microns to about 14 microns or 3 to 8 microns. In various embodiments, the individual detector elements of the microbolometer array can be spaced relatively closely apart to at least partially achieve a small and compact system. For example, adjacent detector elements of the array can be spaced apart by a distance in the range from about 7 microns to about 15 microns, or more specifically, in the range from about 9 microns to about 13 microns, such as about 11 microns. Each lens can be spaced apart by a distance in the range from about 20 mm to about 35 mm, such as in the range from about 24 mm to about 30 mm, such as, about 27.5 mm. Similarly, the spatially and spectrally spaced channels can be physically spaced apart by 20 to 35 mm, 24 mm to 30 mm, etc. Although various embodiments of the system are described as including an FPA (which includes, for example, a microbolometer array), certain embodiments include multiple FPAs. In some embodiments, a single optical FPA is used. In some embodiments, the detectors of the optical FPA are configured to detect radiation in the same IR wavelength band.

[0231] The on-board processing electronics of the data acquisition and processing module 1020 can process the IR optical data to detect and / or identify a target substance from the IR radiation received at the optical FPA. For example, module 1020 can be configured to acquire multi-spectral image data and analyze the acquired image data to identify the target substance. For example, the mobile imaging system 1000 disclosed herein can be configured to image a 10 m x 10 m object area at a distance of about 17 m with a resolution of about 0.04 m. In this example, the system 1000 can detect and / or identify any gas leak that generates a gas cloud with a size of at least about 1.5 inches. The detection and identification method can be performed substantially in real time such that if any leak is identified, the user can be alerted.

[0232] As described above, infrared image data captured by system 1000 can be processed on data acquisition and processing module 1020 of imaging system 1000. One way to provide a smaller system 1000 is to use one or more field programmable gate arrays (FPGAs) to process the image data, which are configured to execute methods used in analyzing images captured by optical system 1015. In some embodiments, instead of or in addition to FPGAs, one or more application specific integrated circuits (ASICs) can be used. For example, an ASIC chip can include an FPGA. The (one or more) FPGAs (and / or (one or more) ASICs) can be mounted to and electrically coupled with the (one or more) substrates 1586 shown in Figure 14C and can be physically located near the optical system. For example, an FPGA can include logic gates and read access memory (RAM) blocks designed to quickly implement calculations for detecting the type of gas in a gas cloud. The small size / weight and high performance characteristics of the FPGA can enable on-board computing and analysis within data acquisition and detection unit 1020 worn or carried by a user. Using an FPGA (or similar electronic device) on-board system 1000 can reduce the costs associated with performing image analysis calculations using off-site central servers or larger computing devices. Advantageously, even though implementing complex methods on the limited computing platform provided by the FPGA may be challenging, the embodiments disclosed herein enable on-board computing.

[0233] In addition, implementing calculations with one or more FPGA devices on-board a wearable system can also prevent or reduce communication bottlenecks associated with wirelessly transmitting large amounts of raw data from system 1000 to a remote server or computer. For example, the infrared optical system 1015 disclosed herein can generate up to approximately 380 Mbps of raw image data at 30 frames per second, and visible sensor 1580 can generate approximately 425 Mbps of raw image data at 30 frames per second. The resulting data rate of approximately 800 Mbps is faster than most conventional wireless technologies. Although data compression and / or preprocessing can reduce the raw data rate of visible and IR images, in some embodiments, the IR image data can be compressed only at a ratio of approximately 2:1. Conventional wireless communication devices may not be able to effectively transmit the resulting overall data rate of approximately 192 Mbps. Thus, performing image processing calculations on system 1000 (e.g., on data acquisition and processing module 1020) can reduce the occurrence of or avoid bottlenecks created by wirelessly transmitting raw image data to an off-site central server.

[0234] One challenge in implementing a mobile imaging system is the power requirements of each component of the system, including, for example, the IR optical system 1015, visible sensor 1580, processing electronics, wireless communication module, etc. Advantageously, the mobile infrared imaging system 1000 disclosed herein can be configured to operate for an extended period of time on battery power without the need for recharging or battery replacement 1588. In some arrangements, one or more batteries 1588 can include lithium-ion batteries having a relatively high energy density. Additionally, to help reduce power consumption within the system 1000, the FPGA of the data acquisition and processing module 1020 can be advantageously programmed such that the power consumption is lower than that of other types of processing electronics.

[0235] The system 1000 disclosed herein can advantageously operate for 8 to 36 hours without the need for recharging or battery replacement, or more specifically between about 10 hours and 24 hours without the need for recharging or battery replacement. In some embodiments, the system 1000 can operate for at least about 12 hours without the need for recharging or battery replacement. The components of the data acquisition and processing module 1020, including the imaging optics, focal plane array, and on-board processing electronics, can be configured to operate at a relatively low level of electrical power, e.g., in the range of about 3W to about 10W, or more specifically in the range of about 4W to about 7W, or in the range of about 4W to about 6W, e.g., operating at a power level of about 5W in some embodiments. The components of the data acquisition and processing module 1020, including the imaging optics, focal plane array, and on-board processing electronics, can also be configured to operate at a relatively low total energy level for a single charge of the battery 1588, e.g., at an energy level in the range of about 60 watt-hours (Wh) to about 100 Wh, or more specifically in the range of about 80 Wh to about 95 Wh, or in the range of about 85 Wh to about 90 Wh.

[0236] In addition, for each embodiment disclosed herein, various motion detection and / or compensation techniques can be implemented to account for relatively large-scale motions caused by a user moving his or her head during use. For example, when a user is visiting a well site or other facility, the user may be walking continuously and looking in different directions (e.g., by rotating his or her head). Additionally, vibrations can be introduced by the user's natural instability. Such motions can continuously change the field of view of the system at a relatively fast rate, which can affect the accuracy of methods for determining the identity of substances in a gas cloud or other object. Therefore, it may be desirable to provide improved motion detection and / or compensation techniques to reduce errors associated with user motion.

[0237] IV. Additional Examples of Mobile DAISI Systems

[0238] Additional examples of mobile fractional aperture infrared spectral imaging (DAISI) systems are provided in this section. For example, Figures 15A - 24D The system 1000 shown in FIG. 1 may be used in conjunction with any of the embodiments disclosed above, including, for example, Figures 11A - 14C ) is used in conjunction with the embodiment of the mobile DAISI system 1000 shown in FIG. Moreover, Figures 15A - 24D The imaging components used in Figures 1 - 10C Advantageously, the system 1000 disclosed herein can provide various improvements that enable a multispectral snapshot mode imaging system to be worn or carried by a person.

[0239] As in the above embodiment, Figures 15A - 24D The system 1000 may include components defining at least two optical channels that are spatially and spectrally distinct from one another and an optical focal plane array (FPA). The at least two optical channels may be positioned to transmit infrared (IR) radiation to the FPA. A processing unit including a processor and / or processing electronics may acquire multispectral image data representing a target substance from the received IR radiation. The optical system and processing unit may be contained together in a data acquisition and processing module that is configured to be worn or carried by a person. In some embodiments disclosed in this section, the imaging system may be fixed at a desired location, such as at a petroleum refinery, oil well site, etc.

[0240] A. System Overview

[0241] Figure 15A is a schematic perspective view of a system 1000 according to various embodiments. Figure 15B yes Figure 15A , a schematic rear perspective view of system 1000 is shown in FIG. System 1000 may include a data acquisition and processing module 1020, which may be similar to the data acquisition and processing modules described above. For example, data acquisition and processing module 1020 may include a housing 1640 within which the optical components of system 1000 are housed. System 1000 may include an optical window 1606 and a visible light imaging system 1680. Window 1606 may be configured to transmit infrared radiation from an object to internal optical components within housing 1640. In some embodiments, window 1606 comprises germanium. Window 1606 and visible light imaging system 1680 may be the same as or similar to the windows and visible light systems described above.

[0242] like Figure 15BAs shown, the data acquisition and processing unit 1020 may include any suitable number of power and / or signal connections to a computing device. For example, the data acquisition and processing unit 1020 may include a data connector 1681 to provide data communication between the data acquisition and processing unit 1020 and the computing device. The data acquisition and processing unit 1020 may also include a power connector 1682 to supply power to the data acquisition and processing unit 1020. In some arrangements, the data acquisition and processing unit 1020 may include a communication module 1024 that may provide wireless (and / or wired) data communication with external computing devices such as laptop computers, tablet computers, smart phones, etc. Additionally, the data acquisition and processing unit 1020 may include one or more batteries to supply power to the system 1000.

[0243] The data acquisition and processing unit 1020 may be configured to be worn or carried by a person. The combination of components described herein may advantageously enable the optical components and processing electronics to fit within a small form factor sufficient to be worn or carried by a person. For example, the data acquisition and processing unit 1020 may have dimensions and weight (or mass) selected to be easily worn or carried by a human user to any suitable location (e.g., for monitoring potential gas leaks at an oil facility and performing infrared imaging). As Figure 15A shown, the size and shape of the data acquisition and processing unit 1020 may be designed to fit within a box-shaped boundary having dimensions length X x height Y x width Z. The volume of the data acquisition and processing unit 1020 may be in the range of 5 cubic inches to 40 cubic inches, in the range of 9 cubic inches to 30 cubic inches, in the range of 10 cubic inches to 30 cubic inches, in the range of 10 cubic inches to 25 cubic inches, in the range of 10 cubic inches to 20 cubic inches, or in the range of 10 cubic inches to 15 cubic inches. In some embodiments, the volume of the data acquisition and processing unit 1020 may be in the range of 15 cubic inches to 25 cubic inches, in the range of 17 cubic inches to 24 cubic inches, or in the range of 19 cubic inches to 23 cubic inches.

[0244] The length X can be in the range of 3 inches to 8 inches, in the range of 3.5 inches to 6 inches, in the range of 4 inches to 6 inches, or in the range of 5 inches to 6 inches. The height Y can be in the range of 1 inch to 5 inches, in the range of 1 inch to 3 inches, in the range of 1.5 inches to 2.5 inches, or in the range of 2 inches to 2.5 inches. The width Z can be in the range of 1 inch to 5 inches, in the range of 1 inch to 3 inches, in the range of 1 inch to 2.5 inches, or in the range of 1 inch to 2 inches. For example, the width Z can be in the range of 1.25 inches to 2 inches, in the range of 1.5 inches to 2 inches, or in the range of 1.6 inches to 1.9 inches.

[0245] The weight of the data acquisition and processing unit 1020 can be in the range of 0.5 pounds to 5 pounds, in the range of 0.5 pounds to 3 pounds, in the range of 0.75 pounds to 2.5 pounds, in the range of 1 pound to 2.5 pounds, in the range of 1 pound to 2 pounds, or in the range of 1.25 pounds to 1.75 pounds.

[0246] Figure 15C is a schematic front perspective view of the system 1000 according to various embodiments. Figure 15C The components of the system 1000 can be the same as Figures 15A - 15B the components of. However, in Figure 15C the embodiment of, the housing 1640A can be included, and the housing 1640A is configured to be used in combination with locations classified in Class 1, Division 1 of the National Electrical Code (NEC) (available at necconnect.org). For example, Figure 15C the housing 1640A can be sufficiently sealed to prevent gas from entering the housing 1640A. As another example, Figure 15C the housing 1640A can be of a type that is generally considered explosion-proof. The processing electronics and other components within the data acquisition and processing unit 1020 can be passively cooled without the need for external airflow from the external environment (e.g., ambient air) to enter the data acquisition and processing unit 1020. In some embodiments, the data acquisition and processing unit 1020 can be filled with gas to cool the internal components. For example, in some embodiments, the data acquisition and processing unit 1020 and the housing 1640A can be filled with nitrogen. Figure 15C The system 1000 shown in can be fixed at a permanent location (e.g., an oil well site or other petroleum facility), or can be configured for a mobile user (e.g., worn or carried by a user).

[0247] Figure 15DFIG. 0 is a schematic system diagram of a mobile computing device 1600 having a first port 1602 configured to be electrically and physically coupled to a DAISI system 1000, such as any mobile DAISI system disclosed herein. The mobile computing device 1600 can be any suitable type of mobile computing device, e.g., a computing device configured to be worn or carried by a person. For example, the mobile computing device 1600 can include a mobile smart phone, a tablet computing device, a laptop computer, etc.

[0248] The DAISI system 1000 can include a data acquisition and processing unit 1020 as described herein. The data acquisition and processing unit 1020 can be included within and / or coupled to a housing 1640B. The DAISI system 1000 can include an optical system 1610 included within the data acquisition and processing unit 1020 and / or the housing 1640B. The optical system 1610 can include various optical components of the DAISI system that cooperate to acquire multispectral image data, including, for example, optical filters, lenses, and optical detectors. For example, the optical system 1610 can include a plurality of spectrally and spatially distinct optical channels along which infrared radiation can be transmitted to a detector.

[0249] In some embodiments, the data acquisition and processing unit 1020 and / or the housing 1640B can include a processing unit 1611 having processing circuitry configured to analyze the acquired image data to detect and / or identify a target substance. In the illustrated embodiment, the processing unit 1611 that analyzes the acquired image data is disposed within and / or coupled to the data acquisition and processing unit 1020 and / or the housing 1640B. However, in other embodiments, the processing unit 1611 can be disposed within the mobile computing device 1600 and can form part of the mobile computing device 1600.

[0250] The data acquisition and processing unit 1020 and / or the housing 1640B may include a second port 1603 configured to mate with the first port 1602 of the mobile computing device 1600. The ports 1602, 1603 may be any suitable type of data and / or power port. For example, the ports 1602, 1603 may include ports used as conventional power ports, audio ports, or other ports on mobile smartphones and / or tablet computing devices. In various embodiments, the ports 1602, 1603 may conform to various industry standards, such as Universal Serial Bus (USB) standards (e.g., USB Type-C, USB 3.1, etc.) (available at usb.org). As another example, the ports 1602, 1603 may be wireless communication ports utilizing any desired wireless technology (e.g., via Bluetooth, WiFi, etc.), such that the mobile computing device 1600 and the DAISI system 1000 can communicate even without a physical connection.

[0251] Beneficially, Figure 15D The arrangement shown in FIG can enable a user to obtain a plug-and-play mobile DAISI system 1000 and removably connect the system 1000 to his or her personal mobile computing device 1600. The system 1000 can be preloaded with software instructions that cooperate with the operating system of the mobile computing device 1600 to operate the optical and processing components of the mobile computing device 1600. In other arrangements, the user can download software to the mobile computing device 1600, and the downloaded software instructions can control the operation of the DAISI system 1000. In some embodiments, the DAISI system 1000 includes both optical components and processing electronics (e.g., data acquisition and processing unit 1020) so that the system 1000 can perform image acquisition and data processing to detect and / or identify target substances. The system 1000 can send data about the detected and / or identified substances to the mobile computing device 1600, which can display the information to the user through a suitable user interface (e.g., a display and / or speaker). In some embodiments, the DAISI system 1000 may include a user interface (e.g., a display and / or a speaker) such that the system 1000 can directly alert the user of detected and / or identified substances even when the mobile computing device 1600 is not coupled to the DAISI system 1000. As just one example, the DAISI system 1000 may include a display (such as a flashing light) and / or a speaker that alerts the user (i.e., provides an alarm to the user) when one or more target substances are detected and / or when the concentration of one or more target substances is detected to be greater than a predetermined threshold concentration.

[0252] In other embodiments, the DAISI system 1000 may include only optical components (e.g., an optical window, a plurality of optical filters, a plurality of lenses, and an optical detector), and the processing electronics may be housed in the mobile computing device 1600. In such an arrangement, the DAISI system 1000 may be configured to acquire image data from a scene (with or without pre-processing techniques) and may transmit the acquired image data to the mobile computing device 1600. The processing electronics of the mobile computing device 1600 may be configured with software instructions that, when executed by the processing electronics, process the acquired image data to detect and / or identify one or more target substances. The detected and / or identified target substances may be transmitted to a user via a user interface (e.g., a display and / or a speaker). In some embodiments, the housing may include the optical system and a processing unit having processing circuitry configured to analyze the acquired image data to detect and / or identify the target substances.

[0253] Thus, in various embodiments, the DAISI system 1000 can include a housing 1640B having an optical system 1610 disposed therein. The optical system 1610 can include the optical components described herein, including, for example, optical components defining a plurality of spectrally and spatially distinct optical channels (such as a plurality of filters and a plurality of lenses spaced apart from the filters) and an optical detector. As explained herein, each of the plurality of optical channels can be positioned to transmit IR radiation incident on the optical system 1610 toward the optical detector. A second port 1603 can be in data communication with the optical detector and configured to be electrically and physically connected to the mobile computing device 1600 to transmit image data collected by the optical detector to the mobile computing device 1600. Furthermore, the housing 1640B can include electronic circuitry 1616 in communication with the second port 1603. The electronic circuit system 1616 may be configured to receive an indication from or send an indication to the mobile computing device 1600 that the mobile computing device 1600 is electrically and physically connected to the port 1603 , for example, via the first port 1602 .

[0254] The electronic circuit system 1616 of the housing can be configured to verify the identifier sent from the mobile computing device 1600 to authenticate that the mobile computing device 1600 is authorized to receive the captured image data. For example, when the user connects the second port 1603 to the first port 1602, the corresponding circuit system in the mobile computing device 1600 can send an identifier to the electronic circuit system of the housing to request access to the captured image data and verify the authenticity of the user associated with the mobile computing device 1600. If the mobile computing device 1600 is verified by the electronic circuit system 1616, the electronic circuit system 1616 can include a switching circuit system that allows the captured image data to be transmitted through the port to the mobile computing device 1600. In some embodiments, the electronic circuit system 1616 can be part of the processing unit 1611.

[0255] Accordingly, Figure 15D The system 1000 shown in FIG. can be sufficiently miniaturized so that it can be used in small mobile computing devices such as mobile smart phones and tablet computers. In various embodiments, for example, the housing 1640B in which the optical system 1610 and the processing unit 1611 are provided can have a volume in the range of 0.25 cubic inches to 10 cubic inches, in the range of 0.25 cubic inches to 8 cubic inches, in the range of 0.5 cubic inches to 8 cubic inches, in the range of 0.5 cubic inches to 5 cubic inches, in the range of 0.5 cubic inches to 3 cubic inches, or in the range of 0.5 cubic inches to 2 cubic inches.

[0256] The system 1000 can be miniaturized in various ways. In some embodiments, the optical system and / or the processing unit can be produced using wafer-level or chip-level processing techniques. For example, as explained herein in Part IV.E.1, semiconductor processing techniques such as deposition, lithography, and etching can be used to pattern the filter array of the optical system. In some embodiments, the lens array and the detector array can also be fabricated using such wafer-level or chip-level techniques.

[0257] Figure 15E is a schematic system diagram of a mobile computing device 1600 according to another embodiment. In Figure 15E FIG., the DAISI system 1000 is integrated within a housing 1640C that defines the body of the mobile computing device 1600. Figure 15EThe mobile computing device 1600 can include any suitable type of mobile computing device, such as a mobile smart phone or a tablet computer. The DAISI system 1000 and the mobile computing electronic device 1601 can be disposed together within the housing 1640C of the mobile computing device 1600. The DAISI system 1000 can include any mobile DAISI system disclosed herein. The mobile computing electronic device 1601 can include processing electronics configured to control the operation of the conventional mobile computing device 1600. For example, the mobile computing electronics 1601 can include various communication platforms, including circuitry configured to transmit and receive cellular data (e.g., voice data and / or multimedia data), wireless data packets, and the like. The mobile computing electronics 1601 can include various other applications used in mobile devices such as mobile smart phones and / or tablet computers.

[0258] Figure 16A is a schematic diagram of the DAISI system 1000 that can be used in accordance with any of the embodiments disclosed herein. Figure 16A The system 1000 can include an optical system 1610 in electrical communication with a processing unit 1611. Figure 16A Illustrates a single optical channel 1626; however, as explained herein, the system 1000 can include a plurality of optical channels 1626 that are different from each other spectrally and spatially. The optical system 1610 can include a filter 1620, a lens 1622 including a plurality of lens elements L1, L2, L3, an optical window 1623, and an optical detector 1624. The filter 1620 can include any filter described herein, and the filter can be an infrared filter. Although only a single filter 1620 is illustrated in Figure 16A only a single filter 1620 is illustrated, the DAISI system 1000 can include a plurality of filters that are different from each other spatially and spectrally, and these filters can be arranged in a two-dimensional array, as explained herein.

[0259] The lens 1622 of the optical channel 1626 shown may include a plurality of lens elements L1, L2, L3, which are arranged adjacent to each other or relative to each other along the optical axis, for example, between an object 1625 (such as a gas cloud) and a detector 1624. As explained herein, the dimensions of the lens elements L1, L2, L3 can be selectively designed to improve the sensitivity of the optical system 1610 and improve the image quality. Like the filter 1620, the plurality of lenses 1622 can be arranged in a two-dimensional array and can be arranged along the optical axis relative to the filter 1620 or spaced apart from the filter 1620. The optical window 1623 can be provided behind the lens 1622, and the detector 1624 can be provided behind the optical window 1623 and can be configured to convert the collected infrared image data into an electric current. The detector 1624 can be any suitable type of detector, including those disclosed herein, such as an optical focal plane array (FPA). As an example, the detector 1624 can include one or more microbolometers. The detector 1624 can be in electrical communication with the processing unit 1611. Variations in the optical design are possible. For example, additional elements such as baffles and / or diaphragms can be included. Filters such as the filter 1620 and other filters can be combined with lenses and / or windows.

[0260] Figure 16B is a schematic front perspective view of the DAISI system 1000, where the housing is removed only for the purpose of illustration. Figure 16C is Figure 16B a schematic rear perspective view of the system 1000. As Figure 16B and 16C shown, the shutter 1621 can be provided behind the optical window 1606. As described below, the shutter 1621 can include a rotating shutter that rotates to switch between one or more calibration modes and an operating imaging mode. The optical system 1610 can be provided behind the shutter 1621, and the processing unit 1611 can be provided behind the optical system 1610. The optical system 1610 can include the optical components described herein that enable the collection of multi-spectral infrared image data. The processing unit 1611 includes processing electronics that can be configured to process the collected multi-spectral infrared image data to detect and / or identify a target substance. For example, the processing unit 1611 can include or be similar to Figure 12 the processing unit 1021 and the associated disclosure.

[0261] In Figure 16B as well as Figure 15CIn the example of FIG. 1 , visible light imaging system 1680 is shown as being closely positioned to (e.g., just above) the divided aperture infrared spectral imaging (DAISI) system. Other suitable arrangements may be provided if desired. As an example, visible light imaging system 1680 may be omitted entirely. As another example, housing 1640A (see FIG. 1 ) may be positioned adjacent to (e.g., just above) the divided aperture infrared spectral imaging (DAISI) system. Figure 15C ) can be divided into two or more sections, one of which can contain a visible light imaging system module and one of which can contain a DAISI system. Such an arrangement can facilitate servicing of system 1000, including replacing visible light imaging system 1680 with another visible light imaging system according to the needs and desires of the user. As an example, system 1000 can be provided to enable a user to replace at least a portion of visible light imaging system 1680 with one having a zoom lens. System 1000 can facilitate such replacement by providing visible light imaging system 1680 relatively separate from the DAISI system and / or contained in a separate portion of housing 1640A.

[0262] Visible light imaging system 1680 can include any desired focal length lens, including a zoom lens having a varying focal length. The zoom lens in visible light imaging system 1680 can include an actuator, motor, or other similar device that drives lens elements within the zoom lens to adjust the focal length (e.g., magnification) of the lens in response to a control signal (which is typically received locally by circuitry in system 1000 or remotely by an external device and by system 1000 over a communication channel).

[0263] Figure 16D is a schematic front perspective view of the optical system 1610. Figure 16D As shown, the optical system 1610 may include a shutter 1621, a support 1626, and an optical detector 1624. Figure 16D In the embodiment, optical components such as the filter 1620 and the lens 1622 may be disposed in the support 1626 . Figure 16E is a schematic perspective cross-sectional view of optical system 1610 , with the shutter omitted for illustrative purposes. Figure 16E The filter array 1620 and the lens elements L1, L2, L3 of the lens 1622 are shown being supported by a support 1626. Figure 16E As shown, filter array 1620 can fit within the aperture of lens holder 1627. Additional features of optical system 1610 are described in detail below.

[0264] like Figure 16EAs shown, lens element L1 can generally lie in a common plane. Similarly, lens elements L2, L3, and filter 1620 can generally lie in their own common plane. If desired, some or all of the optical components associated with one or more of the spectral channels (e.g., lens elements L1, L2, and L3, and filter 1620) can be offset from the optical components of the remaining spectral channels in a direction along the optical axis of system 1000 (i.e., in a direction perpendicular to the common plane). In general, any channel can be offset in any direction (toward or away from the detector) and by any amount, as desired. By way of example, the optical components of one or more channels can be offset closer to detector 1624 by approximately 10 microns, approximately 10-20 microns, approximately 20 microns, approximately 20-30 microns, approximately 30 microns, approximately 10-30 microns, approximately 10-50 microns, approximately 10-100 microns, greater than approximately 100 microns, less than 100 microns, less than 50 microns, less than 30 microns, greater than 30 microns, greater than 50 microns, etc. The optical components of one or more channels may also be moved away from the detector 1624 by a similar amount.

[0265] In at least some arrangements, the position of filters 1620 relative to lens elements L1, L2, and L3 can also be varied on a per-channel basis. As an example, for some channels, a first set of filters 1620 can be positioned behind one or more of lens elements L1, L2, and L3, and in other channels, a second set of filters 1620 can be positioned in front of lens elements L2, L2, and L3.

[0266] Shifting the optical elements of at least one spectral channel closer to (or further away from) detector 1624 can facilitate imaging of a wider or specific range of infrared wavelengths. In some embodiments, the lenses of one or more spectral channels can be approximately 20 microns toward detector 1624. Shifting the lens position by approximately 20 microns can enable these channels to properly focus incident IR radiation having a wavelength between 3 and 8 microns. The remaining (i.e., unshifted) lenses can properly focus incident IR radiation having a longer wavelength of approximately 8 to 14 microns.

[0267] As an example, the lens elements L1, L2, and L3 of the four channels in the corners of system 1000 ( Fig.19The channels 1, 4, 9, and 12 in the perspective view) can be offset by approximately 20 micrometers from the other channels towards the infrared detector 1624. The offset of the four channels in the corners can enable the offset channels to image objects having a different (e.g., shorter) wavelength than the remaining channels. In particular, the offset channels can propagate light of shorter wavelengths. The refractive index of the materials used in L1, L2, L3 can vary with wavelength. Thus, the focal length of the imaging optics in these channels can be shorter. Without reducing the distance between the imaging optics and the detector array, the image will be out of focus. Similarly, by reducing this distance to the detector array, the image can be more focused. Thus, the distance can be reduced by moving the lenses (e.g., L1, L2, L3) closer to the detector array and thereby providing better focus for shorter wavelengths (such as wavelengths extending from 8 micrometers down to 3 micrometers) (e.g., compared to wavelengths of 8 to 14 micrometers). Thus, the offset along the optical axis can provide increased focus for infrared radiation of different wavelengths incident on the detector 1624. Thus, the offset along the optical axis can reduce the focus difference of the channels operating at different wavelengths.

[0268] B. Rotating Shutter

[0269] As explained above with respect to Figure 1-4 it may be important to provide one or more reference surfaces for calibrating the DAISI system. For example, as described above, in some embodiments, the systems disclosed herein can utilize one or more shutters having known and / or measured temperatures. To calibrate the system, one or more shutters (or (one or more) other reference surfaces) can be placed along the optical axis of the system, and the optical detector array can acquire infrared image data of the shutter. The measurements at the detector array can be used to estimate the gain and / or offset of the pixels in order to accurately estimate the concentration of an object (such as a gas cloud). In some embodiments, as described above, the system can utilize multiple shutters or surfaces at a corresponding plurality of known and / or measured temperatures. The absolute temperature difference between the shutters or surfaces can be measured at the detector array, and as explained herein, the measured temperature difference can be used to measure the temperature at the object.

[0270] Figure 17A is Figure 16B and 16DFront elevation plan view of the shutter 1621 as shown. The illustrated shutter 1621 may include a rotating shutter assembly configured to rotate about an axis parallel to the optical axis of the system. The shutter 1621 (or shutter assembly) may include a shutter frame 1706 and a shutter body 1701 rotatably mounted to the shutter frame 1706. For example, the shutter 1621 may include a shaft 1705 disposed within an aperture of the shutter frame 1706. The shutter drive system 1708 may be activated to rotate the shaft 1705 about an axis parallel to the optical axis of the system. The drive system 1708 may include any suitable drive components for applying rotation to the shaft 1705. For example, the drive system 1708 may include a drive motor and one or more gears (or other clutch mechanisms) to apply rotation to the shaft 1705. The shaft 1705 may be fixed to the shutter body 1701 such that rotation of the shaft 1705 applies rotation to the shutter body 1701.

[0271] The shutter body 1701 may include a plurality of separate and distinct regions 1702, 1703, 1704, 1710 circumferentially spaced from each other on the shutter body 1701. In the illustrated embodiment, for example, the shutter body 1701 may include a first reference region 1702, a second reference region 1703, an infrared imaging region 1704, and a visible imaging region 1710. In some embodiments, the first reference region 1702 and / or the second reference region 1703 may be opaque to infrared radiation. The system 1000 may include an infrared imaging aperture 1709, which may correspond to the front aperture of the system 1000. For example, during operation of the system 1000, at least infrared radiation from an object may pass through the infrared imaging aperture 1709 and reach the optical elements (e.g., filters, lenses, etc.) of the system 1000. The system 1000 may also include a visible imaging aperture 1711 through which at least visible light from an object is transmitted. The visible imaging aperture 1711 is at least transparent to visible light such that visible light from the object passes through the aperture 1711 and reaches the visible light imaging system 1680, which may include a visible light sensor to capture visible light image data from the object.

[0272] Processing electronics may be provided in the processing unit 1611 to control the operation of the drive system 1708. The processing electronics may include one or more processors programmed to instruct the motor to rotate the rotary shaft 1705 about its axis of rotation. Rotation of the rotary shaft 1705 and the shutter body 1701 causes regions 1702, 1703, 1704, 1710 to also rotate. To calibrate the system 1000, the drive system 1708 may rotate the shutter body 1701 such that the first reference region 1702 is substantially aligned with the infrared imaging aperture 1709. The first reference region 1702 may be at a known or measured first temperature. For example, in some embodiments, the first reference region 1702 may be actively maintained at a predetermined temperature by one or more heating or cooling elements. In some embodiments, the first temperature of the first reference region 1702 may be monitored (with or without active heating or cooling) by one or more temperature sensors (e.g., thermocouples, etc.). Thus, the system 1000 may accurately measure or otherwise store an approximate temperature of the first reference region 1702. When the first reference region 1702 is aligned with the infrared imaging aperture 1709, the optical detector may acquire first calibration image data representative of the first temperature of the first reference region 1702.

[0273] Similarly, the drive system 1708 may be activated to rotate the shutter body 1701 such that the second reference region 1703 is substantially aligned with the infrared imaging aperture 1709. Like the first reference region 1702, the second reference region 1703 may be actively maintained at a second predetermined temperature by one or more heating or cooling elements. In some embodiments, the second temperature of the second reference region 1703 may be monitored (with or without active heating or cooling) by one or more temperature sensors (e.g., thermocouples, etc.). Thus, the system 1000 may accurately measure or otherwise store an approximate temperature of the second reference region 1703. When the second reference region 1703 is aligned with the infrared imaging aperture 1709, the optical detector may acquire second calibration image data representative of the second temperature of the first reference region 1703, which may differ from the first temperature of the first reference region 1702 by a known and / or predetermined amount.

[0274] During operation (e.g., when calibration is complete and the user desires to acquire image data of an object), the drive system 1708 can rotate the shutter body 1701 such that the infrared imaging region 1704 is substantially aligned with the infrared imaging aperture 1709 of the DAISI system 1000. The visible imaging region 1710 of the shutter body 1701 can be spaced relative to the infrared imaging region 1704 of the shutter body 1701 such that when the infrared imaging region 1704 is aligned with the infrared imaging aperture 1709 of the system 1000, the visible imaging region 1710 is also aligned with the visible imaging aperture 1711 of the system 1000. When the infrared imaging region 1704 and the visible imaging region 1710 are aligned with the respective apertures 1709, 1711, infrared radiation from the object can pass through the infrared imaging region 1704 and the infrared imaging aperture 1709 and reach the infrared imaging optics. Similarly, when the infrared imaging region 1704 and the visible imaging region 1710 are aligned with the respective apertures 1709, 1711, visible light radiation from the object can pass through the visible imaging region 1710 and the visible imaging aperture 1711 and reach the visible light imaging system 1680.

[0275] The shutter body 1701 can include any suitable number of reference regions, and the reference regions can be disposed at any suitable location on the body 1701. Additionally, the shutter body 1701 can include embedded processing electronics for controlling the operation of various components, such as one or more temperature sensors, the drive system 1708, active heating and / or cooling elements, etc. Advantageously, Figure 17A the embodiments enable the DAISI system 1000 disclosed herein to efficiently calibrate the system by rotating a single rotating wheel shutter.

[0276] C. Dual Shutter

[0277] Figure 17B is a schematic perspective exploded view of a shutter 1621A according to some embodiments. Figure 17C is a front view of the shutter 1621A in a closed configuration. Figure 17D is a front view of the shutter 1621A in an open configuration. The shutter 1621A can be used with any DAISI system 1000 disclosed herein.

[0278] The shutter 1621A may include a drive system 1708 that includes a first drive element 1708A and a second drive element 1708B. The first drive element 1708A and the second drive element 1708B may include motors configured to apply rotation to corresponding first shutter bodies 1701A and second shutter bodies 1701B. The first drive element 1708A and the second drive element 1708B may be spaced apart from each other along a lateral direction. The first drive element 1708A and the second drive element 1708B may have drive shafts connected to corresponding drive gears 1721A, 1721B, and each drive gear may have a plurality of gear teeth. The drive shafts of the motors (not shown) to which the gears 1721A, 1721B are connected may be disposed in corresponding recesses 1725 of the frame 1720. As Figure 17C and 17D shown, the drive gears 1721A, 1721B may be disposed above the shutter bodies 1701A, 1701B. The drive gears 1721A, 1721B may be separated from the drive elements 1708A, 1708B by the frame 1720.

[0279] Slip rings 1722A, 1722B may be disposed in corresponding holes 1726 of the frame 1720. In some embodiments, the slip rings 1722A, 1722B may be configured to rotate within the holes 1726. Respective gear shafts 1727A, 1727B may be mounted to corresponding flanges of the slip rings 1722A, 1722B. The first shutter body 1701A and the second shutter body 1701B may be fixed to corresponding shutter gears 1723A, 1723B. Retaining washers 1724A, 1724B may be provided to fix the shutter bodies 1701A, 1701B and the gears 1723A, 1723B to the gear shafts 1727A, 1727B.

[0280] As Figure 17C and 17DAs shown, drive gears 1721A, 1721B can be operatively engaged with shutter gears 1723A, 1723B. To rotate shutter bodies 1701A, 1701B, drive elements 1708A, 1708B can be activated to cause rotation of drive gears 1721A, 1721B, which in turn can cause rotation of shutter gears 1723A, 1723B. For example, the gear teeth of drive gears 1721A, 1721B can mesh or interleave with corresponding gear teeth of shutter gears 1723A, 1723B. Rotation of shutter gears 1723A, 1723B can cause shutter bodies 1701A, 1701B to rotate about respective axes parallel to the optical axis of DAISI system 1000. For example, in some arrangements, rotation of shutter bodies 1701A, 1701B can cause slip rings 1722A, 1722B to rotate within apertures 1726.

[0281] As with Figure 17A the embodiments of Figures 17B-17D In embodiments of

[0282] the shutter 1621A can be used to calibrate DAISI system 1000. For example, the first shutter body 1701A can be at a known or measured first temperature. For example, in some embodiments, the first shutter body 1701A can be actively maintained at a predetermined temperature by one or more heating or cooling elements. In some embodiments, the first temperature of the first shutter body 1701A can be monitored (with or without active heating or cooling) by one or more temperature sensors (e.g., thermocouples, etc.). Thus, system 1000 can accurately measure or otherwise store an approximate temperature of the first shutter body 1701A. When the first shutter body 1701A is aligned with the infrared imaging aperture 1709, the optical detector can acquire first calibration image data representative of the first temperature of the first shutter body 1701A.

[0283] Similarly, Figure 17CIn [the figure], shutter 1621A is illustrated in a closed configuration, in which one or more of shutter bodies 1701A, 1701B are aligned with the infrared imaging aperture 1709. In the closed configuration, shutter body 1701A can be disposed in a lateral region between two rotation axes along a lateral direction. In the illustrated arrangement, both shutter bodies 1701A, 1701B are aligned with aperture 1709. In other arrangements, drive system 1708 can independently align each of shutter bodies 1701A, 1701B with aperture 1709. For example, system 1000 can rotate the first shutter body 1701A to align with aperture 1709 to acquire a first calibration measurement, as Figure 17D shown. At the same time, system 1000 can rotate the second shutter body 1701B to its closed position (i.e., aligned with aperture 1709), or can rotate the second shutter body 170B to its open position. To acquire a second calibration measurement, system 1000 can rotate the first shutter body 1701A to expose aperture 1709, and can rotate the second shutter body 1701B to align with aperture 1709. In its closed configuration, shutter body 1701B can be disposed in a lateral region between two rotation axes along a lateral direction. When calibration is completed, drive system 1708 can rotate both shutter bodies 1701A, 1701B to their respective open positions to expose the infrared imaging aperture 1709, as Figure 17D shown. As explained above, infrared radiation from an object (such as a gas cloud) can enter aperture 1709 and impinge on imaging optics (such as filter 1620, lens, etc.).

[0284] D. Lens Array

[0285] The divided-aperture infrared spectroscopic imaging (DAISI) systems described herein, including the DAISI system disclosed in Part II above and the mobile DAISI system disclosed in Part III above, can include features such as a lens array formed of a monolithic lens substrate, a lens array formed of individual lens substrates, a patterned optical filter, an array of individual optical filters, and a cooling module coupled to components such as an optical focal plane array (FPA) unit and a lens assembly.

[0286] As described herein, a DAISI system can include a lens assembly 1502 that includes a lens array 1002. As disclosed in connection with Figure 18A each lens of lens array 1002 can at least partially define or be included in an optical channel to be imaged by FPA unit 1008.

[0287] In at least some embodiments, a baffle 2500 (e.g., in mounting plate 1584) may be provided to reduce or block stray light. The baffle 2500 may reduce or block light entering via one optical channel (which may be associated with one lens) from exiting the lens assembly 1502 via another optical channel (which may be associated with another lens). The baffle 2500 may be formed of any desired material and using any desired technique. As an example, the baffle 2500 may include a metal plate having lens openings formed by mechanical or laser cutting. If desired, the baffle 2500 may be formed of a material having a coefficient of thermal expansion (CTE) similar to or matching that of the substrate 2501. By having a similar or matching CTE, the baffle 2500 and the substrate 2501 may maintain optical performance over a wide temperature range.

[0288] 1. Monolithic substrate for a lens

[0289] As Figure 18A and 18B shown, the lens array 1002 may be formed of one or more monolithic substrates 2501. In other words, multiple lenses (i.e., some or all of the lenses) in the lens array 1002 may share a single common substrate. The monolithic substrate may be formed in a manner that provides lenses associated with multiple optical channels. As Figure 18B shown, all of the lenses of the lens array 1002 may be formed of a single monolithic substrate 2501. In this way, the monolithic lens substrate 2501 may include portions corresponding to the lenses of each optical channel in the DAISI system. For example, the monolithic substrate 2501 may include a lens portion 2502A corresponding to a first optical channel, a lens portion 2502B corresponding to a second optical channel, and so on.

[0290] Although Figure 18B illustrates the monolithic lens substrate 2501 having multiple lens portions formed by corresponding shaped (e.g., spherical) portions of the substrate, the monolithic lens substrate 2501 may also be a gradient index optical substrate (i.e., the lens substrate 2501 may form GRIN lenses). In such an arrangement, the monolithic substrate 2501 may be formed with a flat surface, but in the same manner as a conventionally shaped lens, having a variation in the refractive index of the substrate material such that light is focused through each lens portion 2502A, 2502B, etc. A lens substrate such as the monolithic substrate 2501 may also be formed with a combination of shaped portions for lens formation and a variation in the refractive index of the substrate material for lens formation.

[0291] The lens substrate 2501 may be formed of any suitable material, including but not limited to silicon, germanium, chalcogenide glass, calcium fluoride, zinc selenide, zinc sulfide, gallium arsenide, cadmium telluride, black diamond-2 TM(BLACK DIAMOND-2 TM )(A chalcogenide made of an amorphous mixture of germanium, antimony, and selenium), AMTIR TM (An amorphous material that transmits infrared radiation), thallium iodide bromide, IR fused silica, sodium chloride, potassium bromide, potassium chloride, sapphire, crystalline quartz, UV fused silica, barium fluoride, calcium fluoride, magnesium fluoride, lithium fluoride, etc. The lens substrate 2501 can preferably be formed of a material that is transparent to infrared wavelengths and / or other wavelengths that the system 1000 is configured to detect, and can be formed of a glassy substance, a crystalline substance, and / or other suitable substances.

[0292] The lens substrate 2501 can be molded into a desired shape (i.e., the respective lens portions 2502A, 2502B, etc. can be formed by a molding process). When the lens substrate 2501 is formed of glass or other amorphous materials, the molding process may be particularly suitable. The lens substrate 2501 can also be ground or cut into a desired shape (i.e., the respective lens portions 2502A, 2502B, etc. can be formed by diamond cutting or other methods). When the lens substrate 2501 is formed of a crystalline substance or other similar substances, the grinding and cutting processes may be particularly suitable. Generally, regardless of whether the lens substrate 2501 is formed of an amorphous substance, a crystalline substance, or other substances, a combination of molding, grinding, cutting, and other similar processes can be used to shape the lens substrate 2501.

[0293] 2. Individual lens substrates

[0294] As Figure 18C and Figures 18D-18E shown, the lens array 1002 can be formed by an array of individual lens substrates, such as lens substrates 2504A, 2504B, etc. (also referred to herein as individual lenses). By forming the lens array 1002 from an array of individual lenses, the manufacture of the lens array 1002 can be simplified (i.e., in at least some cases, producing multiple individual lenses may be simpler than producing a monolithic substrate including multiple lens portions). The individual lenses 2504A, 2504B, etc. in the lens array 1002 can be formed of any suitable material, including those described herein in connection with the monolithic lens substrate 250! The individual lenses 2504A, 2504B, etc. in the lens array 1002 can be formed using any suitable technique, including those described herein in connection with the monolithic lens substrate 2501.

[0295] The lens array 1002, whether formed from individual lens substrates or a monolithic lens substrate, can be mounted in a lens holder 1584 (also referred to herein as a mounting plate). The lens holder 1584 can be formed from any desired material and using any desired technique. As an example, the lens holder 1584 can be formed from metal and have lens openings formed by mechanical or laser cutting. In at least some embodiments, the lens holder 1584 can be formed from a material having a coefficient of thermal expansion (CTE) similar to or matching that of the lenses in the lens array 1002. By having a similar or matching CTE, the lens holder 1584 and the lenses in the lens array 1002 can maintain optical performance over a wide temperature range. In other words, by having a similar or matching CTE, the lens holder can maintain the optical alignment of the lens portions 2502A, 2502B, etc. or individual lenses 2504A, 2504B, etc., even as the temperature of the entire system changes. As a specific example, the lens holder 1584 can be formed from Kovar (a nickel-cobalt-iron alloy having CTE characteristics substantially similar to those of germanium). can have a CTE of approximately 5.5 x 10 -6 / Kelvin (at temperatures below 200 °C), while borosilicate glass can have a CTE of approximately 3 to 6 x 10 -6 / Kelvin (at temperatures below 200 °C).

[0296] Figure 18D shows Figure 18C an exploded perspective view of an imaging system. Figure 18E shows Figure 18C a cross-sectional view of an imaging system. As Figure 18D and 18E shown, the lens array 1002 can include a plurality of optical layers, such as front lenses 2504A, 2504B, etc.; intermediate lenses 2506A, 2506B, etc.; and rear lenses 2508a, 2508B, etc. In addition, the lens array 1002 can include washers or other mounting structures 2514 and 2516 that hold the front, intermediate, and rear lenses together when the lens array 1002 is assembled with the lens holder 1584. Additionally, the imaging system can include a filter housing 2510 that includes filter arrays 2512A, 2512B, where each filter array corresponds to a specific optical channel and a corresponding set of front, intermediate, and rear lenses. In at least some embodiments, the front, intermediate, and rear lenses can be recessed into the front portion of the lens holder 1584 and secured by the filter housing 2510. Figure 18DThe arrangement can reduce the possibility of stray light (i.e., light that enters the first optical channel and crosses over into the second optical channel). In other words, when the lens is recessed within the lens holder 1584, the lens holder 1584 can operate as a stray light blocking baffle.

[0297] Figure 18D The intermediate lens 2506 and the rear lens 2508 shown in FIG. can be formed using materials similar to those described herein in connection with the lens 2504. Additionally, the intermediate lens 2506 and the rear lens 2508 can be formed using manufacturing techniques similar to those described herein in connection with the lens 2504. In at least some embodiments, the intermediate lens 2506 can have relatively flat front and rear surfaces, while the front lens 2504 and the rear lens 2508 have curved front and rear surfaces. In at least some other embodiments, some or all of the front lens, intermediate lens, and rear lens are formed of GRIN lenses.

[0298] E. Filter Array

[0299] As discussed herein, a gas and chemical imaging system can include an array 2550 of optical filters, such as Fig.19 the array 2550 shown in FIG., which defines spectrally distinct sub-images. These optical filters can each pass different wavelengths or wavelength ranges or bands or sets of wavelengths or sets of wavelength ranges or bands of incident light. In at least some embodiments, some or all of the optical filters include filters that pass different wavelengths or sets of wavelengths (e.g., typically extending from about 1 micron to about 20 microns in wavelength) of incident light in the infrared range. Theoretical diagrams of the transmission characteristics of optical filters that can be used in gas and chemical imaging systems of the type described herein are shown and described in connection with Figure 6A , 6B , 6C and 6D. The optical filters shown and described in connection with Figure 6A , 6B , 6C and 6D are merely illustrative.

[0300] Although the filter and filter array 2550 are generally described herein as being separate from the optical lens array 1002 (and lenses 2502, 2504, 2506, or 2508), the filter may be incorporated into some or all of the lenses of the optical lens array 1002 or on some or all of the lenses of the optical lens array 1002 if desired. In particular, the filter array 2550 may be provided as a coating on some or all of the lenses of the lens array 1002. In an arrangement where the lens array 1002 is formed from a single-piece substrate, the filter array 2550 may be formed from a patterned filter array (as described herein) coated on or integrated within the single-piece substrate. In an arrangement where the lens array 1002 is formed from individual lenses, the filter array 2550 may be formed from individual filters coated on or integrated within some or all of the individual lenses.

[0301] 1. Patterned filter arrays

[0302] As Fig.19 shown, a filter array 2550 may be provided that includes being patterned to form individual optical filters 2512A, 2512B, etc. (in Fig.191, 2, ..., 12 in the system 1000 and having a substrate 2501 with infrared blocking material 2558 disposed between the individual optical filters. Filter array 2550 may also be referred to herein as filter array 454. Each individual optical filter 2512A, 2512B, etc. may pass only the desired infrared radiation for its corresponding optical channel and its corresponding infrared detector. In at least some embodiments, each optical filter selectively passes at least one wavelength or wavelength range or band or set of wavelengths or wavelength ranges or bands within the infrared range of approximately 1 to 20 microns, within the infrared range of approximately 7 to 14 microns, or within the infrared range of approximately 3 to 14 microns or 3 to 8.5 microns. By way of example, one or more spectral channels in system 1000 may have infrared filters (which may be formed from multiple filters) that pass infrared light in both the 3 to 4 micron range and the 6 to 8 micron range (or the 7 to 8.5 micron range, or the 7 to 8 micron range, or other suitable ranges). In other words, system 1000 can include a dual notch infrared filter in at least one spectral channel. Such a dual notch filter is particularly useful in detecting the infrared signature of a specific gas, such as methane, even without information from other spectral channels in system 1000. Notch filters generally attenuate wavelengths that fall outside their pass range. As an example, a dual notch filter that passes infrared light in both the 3 to 4 micron and 6 to 8.5 micron ranges can attenuate wavelengths shorter than 3 microns, wavelengths between 4 and 6 microns, and wavelengths longer than 8.5 microns. Infrared blocking material 2258 can help reduce optical crosstalk or stray light, where infrared light enters a first optical channel but undesirably passes into a second optical channel.

[0303] Individual optical filters 2512A, 2512B, etc. can be formed on substrate 2501 using any suitable technique or combination of techniques. As an example, the optical transmission characteristics of the individual optical filters can be adjusted by varying the type of one or more materials deposited at the location of each optical filter, the thickness of one or more materials formed at the location of each optical filter, the number of layers of one or more materials at the location of each optical filter, etc. In at least some embodiments, the optical filter can be an interference filter and can be a bandpass filter, a highpass filter, a lowpass filter, or a bandstop filter. In at least some embodiments, the optical filter can be formed by one or more thin film layers that determine the optical transmission characteristics of the filter. Interference coatings with different designs (e.g., having different numbers or arrangements of layers, different materials, different thickness layers, etc.) can be used. Forming the individual optical filters 2512A, 2512B, etc. may involve processing steps such as masking, etching, deposition, planarization, doping, stripping mask materials, etc. In this way, one or more optical filters can be selectively processed while protecting one or more other optical filters).

[0304] The infrared blocking material 2558 can be used as a baffle, an aperture stop, or a field stop, and can be patterned onto the substrate 2501 in the space between the filters 2512. The infrared blocking material 2558 can be formed of any suitable material, such as chromium, which blocks light including stray light between the filters 2512. In at least some embodiments, the infrared blocking material 2558 can be formed to achieve apodization (i.e., a smoothly varying transmission profile, a transmission profile that varies smoothly according to the position in the filter array, etc.). In particular, the infrared blocking material 2558 can provide a slowly varying gradient baffle, aperture stop, or field stop that has a maximum transmittance near the center of the filter, a minimum or zero transmittance in the space between the filters, and some intermediate transmittance near the edge of the filter. The infrared blocking material 2258 can be formed in this way using suitable patterning and processing techniques.

[0305] 2. Individual or cutting filters

[0306] Figures 20A-20CAn alternative arrangement of filter array 2550 is illustrated, in which filter array 2550 is formed from individual filters. In this arrangement, batches of filters are created using appropriate processing steps (as described herein in conjunction with patterned filters). Each batch can include multiple copies of a particular filter (i.e., one of filters 2512A, 2512B, etc.). After the batch is formed, the multiple copies of the particular filter can be separated or cut to create individual copies of the particular filter. The individual copies of each filter forming filter array 2550 (which have been separated or cut from their respective batches) can then be assembled into filter array 2550. With this type of arrangement, processing of each batch can be somewhat simplified because each substrate being processed only includes a single type of filter. The benefits of simplified batch processing may outweigh any additional complexity involved in separating or cutting and subsequently assembling the individual filters into filter array 2550.

[0307] like Figure 20B and 20C As shown in the rear view of the filter housing 2510, the filter housing 2510 may include alignment structures 2560A, 2560B, etc., in which the individual filters 2512A, 2512B, etc. are mounted and aligned. The alignment structures 2560A, 2560B can be formed by grooves, registration features, posts, other suitable elements, or a combination of these and other elements in the filter housing 2510. In at least some embodiments, when assembled to the mounting plate 1584, the individual filters can be secured to the housing 2510 by pressure. If desired, the individual filters can also or alternatively be secured to the housing 2510 by pressure (i.e., by snapping into place in a groove portion of the housing 2510), adhesive, screws, clips, or other fastening elements.

[0308] F. Detector Array

[0309] As discussed herein, a gas and chemical imaging system can include a detector, such as an optical focal plane array (FPA) 1508. FPA 1508 can receive light from a plurality of spatially separated optical channels, for example, with the aid of an optical filter array 2550, and the light can be spectrally distinct. In at least some embodiments, FPA 1508 can be formed from one or more microbolometer arrays configured to detect infrared radiation, as discussed in greater detail herein. In at least some embodiments, individual lenses 2502, 2504, etc., and optical filters 2512 can be laterally spaced apart by a distance in the range of about 2 mm to about 20 mm, about 3 mm to about 10 mm, about 4 mm to about 8 mm, about 4.3 mm, or some other suitable distance. Similarly, the spatially and spectrally spaced channels of FPA 1508 can be physically spaced apart by about 2 to 20 mm, 3 to 10 mm, 4 to 8 mm, about 4.3 mm, etc.

[0310] Figure 21 Also illustrated is that the imaging system may include components such as an FPGA board 2590, a signal conditioning board 2592, and a data communications board 2594. The FPGA board 2590 and the signal conditioning board 2592 may be configured to perform the methods used in the analysis of images captured by the optical system as discussed herein (see, e.g., Figure 12 The data communication board 2594 can be configured to communicate (e.g., via a wired or wireless connection) with at least one device that is physically separate from the imaging system, as discussed herein (see, e.g., Figure 12 (see discussion of communication module 1024 for details).

[0311] 1. TEC Cooling

[0312] like Figure 21As shown, the FPA 1508 can be actively cooled, heated, temperature stabilized, and / or actively thermally controlled using a thermoelectric cooling (TEC) device 2570 that utilizes the Peltier effect (which can also operate as a heater) or using other cooling and / or heating devices. The TEC device 2570 can be coupled to a heat sink 2572 and a heat sink fan 2574. In operation, the TEC device 2570 can transfer thermal energy from the FPA 1508 to the heat sink 2572, and the heat sink fan 2574 can transfer the thermal energy into the surrounding environment. If desired, in addition to or instead of the heat sink fan 2574, the heat sink 2572 can be cooled by liquid cooling. The imaging system can include a temperature sensor thermally coupled to the FPA 1508 or the TEC device 2570. The temperature sensor can be integrated into the FPA 1508, integrated into the TEC device 2570, or can be a separate device. The TEC device 2570 can be configured to monitor the temperature of the FPA 1508 using the temperature sensor and, in response, maintain the FPA 1508 at a target temperature. By keeping the temperature of the FPA 1508 relatively constant, the calibration of the FPA 1508 can be improved or optimized. In particular, the FPA 1508 can be calibrated after the TEC device 2570 cools the FPA 1508 to a desired operating temperature, and then the TEC device 2570 can keep the FPA 1508 at the operating temperature to maintain the calibration. Alternatively, the TEC device 2570 can operate at a maximum or other preset cooling power to maintain the lowest possible temperature of the FPA 1508. Alternatively, the TEC 2570 can maintain the temperature of the FPA 1508 within a certain desired range, e.g., below a first temperature, above a second temperature, etc. In some embodiments, the TEC 2570 can cryogenically cool the FPA 1508. In other embodiments, the TEC 2570 can cool the FPA 1508 to a non-cryogenic temperature, such as ambient temperature, 10°C below ambient temperature, 20°C below ambient temperature, 30°C below ambient temperature, etc., or a temperature independent of the environment, such as -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, etc., and any range within any combination of these temperatures. The TEC device 2570 can be a single-stage TEC cooler or can include multiple stages (e.g., a first TEC stage with a "hot side" cooled by a larger second TEC stage, the first TEC stage itself having a hot side cooled by a heat sink). The temperature at which the TEC unit 2570 cools the FPA 1508 (whether absolute temperature or relative to the environment) can be pre-configured, can be set by the user, or can be determined as part of a calibration process.As an example, the calibration process can involve determining that the FPA 1508 needs to be cooled to a certain temperature (whether absolute or relative to the environment) to achieve a desired performance level. In response, the cooling controller in the imaging system can configure itself based on the results of the calibration to maintain the FPA 1508 at that temperature. In this way, the accuracy of gas and chemical detection of the FPA 1508 can be improved.

[0313] The imaging system can include one or more controllers that control the operation of cooling units such as TEC units 2570 and 2580. The controller can receive inputs from a thermometer (i.e., temperature sensor) coupled to the element being cooled, a thermometer that determines the ambient temperature, other processors and controllers in the imaging system, feedback from the TEC unit or other cooling units, etc. The controller can adjust the operation of the TEC unit in real time to maintain the cooling performance and the desired temperature of the element being cooled.

[0314] 2. TEC cooling of optical devices

[0315] If desired, a thermoelectric cooling (TEC) device 2580 that utilizes the Peltier effect or another cooling / or heating device can be used to actively cool and / or heat a lens assembly 1502 that includes elements such as a lens array 1002, a mounting plate 1584, and a filter housing 2510. The TEC device 2580 can be coupled to a heat sink 2582 and a heat sink fan 2584. In operation, the TEC device 2580 can transfer thermal energy from the lens assembly 1502 to the heat sink 2582, and the heat sink fan 2584 can transfer the thermal energy to the surrounding environment. If desired, in addition to or instead of the heat sink fan 2584, the heat sink 2582 can be cooled by liquid cooling. The TEC device 2580 can be provided with any features and can be operated using any of the techniques discussed herein in connection with the TEC device 2570. As an example, the TEC device 2580 can actively cool the lens assembly 1502 to a cryogenic or non-cryogenic temperature, can use a thermometer to monitor the temperature of the lens assembly 1502, can be a single-stage or multi-stage TEC device, can facilitate calibration and maintain calibration performance, etc. By actively cooling the lens assembly 1502, the accuracy of gas and chemical detection of the FPA 1508 can be improved.

[0316] As schematically shown by thermal connection 2586, the lens assembly 1502 can optionally be actively cooled by a TEC device 2570. The thermal connection 2586 can be a heat pipe 2582 or other device. In other words, the TEC device 2570 can provide primary cooling to the FPA 1508 and secondary cooling to the lens assembly 1502 through the heat pipe 2586, by mounting the lens assembly 1502 to the FPA 1508 and / or the TEC device 2570, or via other devices.

[0317] G. Reduce crosstalk

[0318] A DAISI system (whether installed at a fixed location or a mobile DAISI system) can include a lens array for imaging an object (such as a gas cloud) through an optical detector. For example, as described herein in connection with Figures 18A-18E A DAISI system can include a lens assembly 1502 that includes lens arrays 2504, 2506, and 2508 that at least partially define or are included in an optical channel to be imaged by the FPA unit 1008. In some embodiments described throughout this application, the DAISI system is configured as an infrared (IR) imaging system for imaging an object. An FPA configured to image IR radiation can be expensive, and thus it may be advantageous to position the optical channels closely together or as physically close as possible to increase or maximize the available area of the FPA unit 1008. However, positioning the optical channels closely together can cause unwanted stray light from one optical channel to cross into an adjacent optical channel, also referred to herein as "optical crosstalk". In various embodiments, the lenses can be spaced edge-to-edge within a range of 0 mm to 2 mm, within a range of 0 mm to 1 mm, within a range of 0 mm to 0.5 mm, or within a range of 0.05 mm to 0.5 mm, for example, a distance of about 0.1 mm.

[0319] For example, Figure 22A is a ray trace diagram illustrating an example of optical crosstalk between the optical channels of the lens assembly 1502 shown in Figure 18D Unless otherwise specified, the same reference numerals in Figure 22A represent components that are the same as or similar to the components with the same reference numerals in Figures 18A-18E Figure 22A illustrates various optical elements described in connection with Figures 18A-18E as a collection of optical surfaces (represented as planes in Figure 22A For example, the lens assembly 1502 can include lenses 2504, lenses 2506, lenses 2508, a filter 2512, and an optical window 2607. ( Figure 22A ​Schematically illustrates the optical window 2607 and the front and rear surfaces of each of the lenses 2504, 2506, and 2508. The lens assembly 1502 can be used to image an object 2601 that is spaced apart from the lens assembly 1502 along the axis 2680 of the optical detector 2610. Figure 22A Depicts lenses 2504A, 2506A, and 2508A corresponding to the optical channels 2602A arranged along the axis 2680A. Although Figure 22A Depicts nine different optical channels 2602, any number (two, three, four, five, six, seven, eight, nine, twelve, or more) of optical channels 2602 is possible.

[0320] Each optical channel 2602 is configured to collect light from the object 2601 and transmit the light (represented as light rays 2605) along its corresponding axis 2680 toward the optical detector 2610. The optical detector 2610 can generate data representing an image corresponding to the light received for each optical channel 2602. However, as Figure 22A Shown, due to the angle of incidence of light on the optical surfaces and the refractive properties of the lenses, some light may cross between adjacent optical channels. For example, the light rays 2605A and 2605B are refracted by the lens 2504 into adjacent optical channels and out of the desired optical channel 2605 (in Figure 22A this case, the central optical channel). Thus, a portion of the light incident on one optical channel can cross into an adjacent optical channel (e.g., optical channel 2602A) and be added to the light from the object 2601 when being transmitted by the adjacent optical channel to the optical detector 2610. The additional light from the adjacent optical channel may distort, corrupt, or otherwise interfere with the data corresponding to a given optical channel 2602.

[0321] Thus, in a DAISI system including a lens array with tightly sealed optical channels, controlling stray light is important. The various embodiments disclosed herein employ various techniques that can provide such control to increase, improve, or optimize the illumination of an optical detector while reducing the impact of stray light on the resulting image. For example, a DAISI system can be configured to provide vignetting of the image of the optical channels at the optical detector to remove or at least partially reduce optical crosstalk between the optical channels. The DAISI system can cause vignetting by at least partially reducing the brightness or illumination of light at the periphery or edges of the optical channels. For example, the DAISI system can include one or more baffles or aperture elements that are configured to at least partially block the passage of stray light between the optical channels while allowing the optical channels to transmit light incident on the optical channel. The one or more baffles or aperture elements can also be configured to at least partially block stray light that has passed between the optical channels from reaching the optical detector. Reducing optical crosstalk between optical channels in a tightly sealed lens array system can be important because when optical channels are placed closely together, optical crosstalk between the optical channels can increase, thereby degrading the quality of the data obtained.

[0322] In various embodiments, each system disclosed herein can be used to monitor for potential gas leaks at any suitable installation site, including but not limited to drilling platforms, refineries, pipelines, transportation systems, ships or other vessels (such as offshore oil drilling platforms, trains, tank trucks, petrochemical plants, chemical plants, etc.). Additionally, each system disclosed herein can also be used with any mobile DAISI system, including but not limited to systems worn or carried by a user. Furthermore, each embodiment and aspect disclosed and illustrated herein, for example, with respect to Figures 22A-22G can be used in combination with any feature or any combination of features disclosed and illustrated by this application.

[0323] Figure 22B is an exploded perspective view of a lens assembly 2702 that is configured to at least partially reduce optical crosstalk and that can be used in combination with a DAISI system. The lens assembly 2702 is substantially similar to Figures 18A-18E the lens assembly 1502. Unless otherwise noted, Figure 22B the same reference numerals in Figures 18A-18E denote components that are the same as or similar to the components with the same reference numbers in Figures 18A-18E Although the lens assembly 2702 has been described in connection with the lens assembly 1502, the various features described herein can be used in combination with any other suitable type of optical system. For example, in connection with Figure 22BThe various lenses, lens arrays, and components shown in []. However, the lens assembly 2702 can include any number of lenses and optical elements or any combination of lenses and optical elements that can correspond to a plurality of spatially and spectrally distinct optical channels as described herein.

[0324] The lens assembly 2702 can be designed to block stray light that has passed between one optical channel and another optical channel and entered the other optical channel. In some embodiments, the lens assembly 2702 can also be configured to allow light incident on a given optical channel to be transmitted through that optical channel to a corresponding region of an optical detector (e.g., a detection region as described below in connection with Figure 22D ). In various embodiments, the optical detector can include a single focal plane array. In various other embodiments, the optical detector can include multiple focal plane arrays. For example, the lens assembly 2702 can include at least one baffle 2630 that is configured to control stray light to provide at least partial vignetting of an image at the optical detector. In some embodiments, the lens assembly 2702 can include two baffles 2620 and 2630. Unless otherwise specified, the baffles 2620 and 2630 can be substantially similar to Figures 18A-18E the baffle 2500 and are configured to at least partially block light from passing between optical channels. The baffles 2620 and 2630 can be configured to at least partially block stray light that has passed from an adjacent optical channel from being transmitted to the optical detector. In various embodiments, the baffle is configured to substantially vignette an image at the optical detector array or a portion thereof.

[0325] For example, the baffle 2620 can be configured to reduce or at least partially block light entering via one optical channel from exiting the lens assembly 2702 via another optical channel. In some embodiments, the baffle 2620 is configured to substantially reduce light passing between optical channels. The baffle 2620 can be positioned at the front of the optical channel 2602. In some embodiments, the baffle 2620 can be disposed near the lens 2504 and / or between the lens 2504 and the object ( Figure 22B not shown in []). In another embodiment, alternatively or in combination, the baffle 2620 can be disposed between the filter housing 2510 and the object. In some embodiments, the baffle 2620 can be formed as part of the filter housing 2510 or integrated into a groove of the filter housing 2510 ( Figure 18D shown in []). In one embodiment, the baffle 2620 is disposed as close as possible to the filter housing 2510 within manufacturing tolerances.

[0326] As described in connection with Figures 18A-18EAs described above, the baffle 2620 may include a light attenuation or light blocking surface, for example, a sheet or plate including a light attenuation or blocking material (e.g., metal or plastic), which is formed with a plurality of openings 2622 (e.g., also referred to as apertures) by mechanical or laser cutting, for example. Each opening 2622A, 2622b, etc. may be disposed along the axis of the corresponding optical channel (e.g., Figure 22A the axis 2680). The openings 2622 may be configured to control the light incident on the optical channel by modifying the optical path entering the optical channel. For example, each opening 2622 may be configured to block stray light that would otherwise be incident at the outer edge of the corresponding optical channel. The openings 2622 may also be configured to allow the light incident at the central region of the optical channel to be transmitted to an optical detector ( Figure 22B not shown in). Thus, the light is at least partially blocked or substantially blocked such that stray light does not pass into an adjacent optical channel.

[0327] Although the plurality of openings 2622 are illustrated as having a circular shape in Figure 22B , it should be appreciated that the openings 2622 may have any suitable shape (e.g., oval, rectangular, square, etc.) in order to vignette the image at the optical detector. The shape, dimensions, and location of the openings 2622 may be based on the optical properties and arrangement of the elements in the lens assembly 2702. For example, the lens assembly 2702 may include an optical aperture layer 2650 that includes a plurality of optical apertures 2655a, 2655b, etc. corresponding to each optical channel. In one embodiment, the optical aperture layer 2650 may be disposed between the lenses 2504 and 2506. The dimensions of the plurality of openings 2622 may be at least partially based on the location of the optical aperture layer 2650 within the lens assembly 2702. For example, for Figure 22B the illustrated embodiment, each opening 2622 has a lateral dimension (e.g., diameter, side, etc.) in the range of 3 mm to 6 mm or in the range of 4 mm to 5 mm, for example, a dimension of about 4.4 millimeters with a tolerance of about + / -0.010. The thickness of the baffle may be in the range of 0.05 mm to 0.5 mm, in the range of 0.1 mm to 0.3 mm, for example, about 0.2 mm. Although the openings 2622 are described herein as each having the same dimensions, it should be appreciated that this is not intended to be limiting and each opening 2622 may have different dimensions and / or shapes. In some embodiments, the structure and location of the baffle 2620 may be based on an optical system that has been optimized for any suitable application.

[0328] In some embodiments, a baffle 2630 is provided that can be similar to the baffle 2620 and is also configured to at least partially provide vignetting of the image of the object. The baffle 2630 can be positioned at the rear of the optical channel, closer to the optical detector array than to the front element of the lens assembly. In some embodiments, the baffle 2630 can be disposed near the lens 2508 and between the lens 2508 and the optical detector. In another embodiment, alternatively or in combination, the baffle 2630 can be disposed between Figure 18D the lens holder 1584 and the lens 2508. In some embodiments, the baffle 2630 can be formed as part of or attached to the lens holder 1584. In one implementation, the baffle 2630 is disposed as close as possible to the optical detector within manufacturing tolerances.

[0329] Similar to the baffle 2620, the baffle 2630 can include a light attenuation or light blocking surface, such as a metal or plastic sheet or plate, having a plurality of openings 2632 formed, for example, by mechanical or laser cutting. Each opening 2632a, 2632b, etc. (e.g., also referred to as a field stop) can be disposed along the axis of the optical channel of the lens assembly 2702. The openings 2632 can be configured to control the light transmitted through the optical channel by modifying the optical path to the optical channel. For example, each opening 2632 can be configured to block stray light that has passed between the optical channels so that the stray light is not transmitted to the optical detector. The openings 2632 can also be configured to allow light incident on a given optical channel to be transmitted through the given optical channel to reach the associated optical detector. For example, the baffle 2630 can not affect the light incident on the central region of a given optical channel and / or light having an incident angle that will allow the light to be transmitted through the given optical channel. Thus, the light is blocked so that it does not interfere with the image formed by adjacent optical channels.

[0330] Although the plurality of openings 2632 are shown in Figure 22B as having a rectangular shape, it should be appreciated that the openings 2632 can have any suitable shape (e.g., oval, circular, square, etc.) to vignette the image at the optical detector. As described above with respect to the baffle 2620, the shape, dimensions, and position of the openings 2632 can be based on the optical properties and arrangement of the optical elements in the lens assembly 2702. Thus, the dimensions of the plurality of openings 2632 can be at least partially based on the position and dimensions of the optical stop layer 2650. For example, for Figure 22BIn the illustrated embodiment, each opening 2632 has a lateral dimension (e.g., diameter, side, etc.) in the range of 1 mm to 5 mm, 2 mm to 5 mm, or 3 mm to 4 mm, e.g., about 3.2 millimeters. In various arrangements, the opening 2632 can be polygonal (e.g., square or rectangle) or rounded (e.g., oval or circular). Although the openings 2632 are described herein as each having the same dimension, this is not intended to be limiting, and each opening 2632 can have different dimensions and / or shapes. In some embodiments, the baffle 2630 can be configured for an optical system designed or optimized for any suitable application and has a design based on the components of the optical system.

[0331] The lens assembly 2702 can be used in conjunction with an optical system including any suitable optical arrangement, such as one or more lenses (e.g., multiple lenses) and / or one or more filters (e.g., multiple filters) that transmit light to an optical detector. The lens assembly 2702 is one embodiment of a design described in connection with various DAISI systems, which can vary in design characteristics (e.g., the DAISI system can be mobile or fixed). However, the positions and optical components within the lens assembly 2702 can be modified according to the desired combination with any suitable type of imaging application. For example, the lens assembly 2702 can be used with any suitable type of infrared imaging system or camera to control stray light to maintain the optical performance of the system. Based on the desired application, the lens assembly 2702 can be optimized for any specific application having any combination or arrangement of elements. Thus, for any suitable application, the various optical elements of the lens assembly 2702 can be modified, moved, removed, etc. For example, for a specific application, the position of the optical aperture 2650 can be changed, or the optical power and / or position of the lenses 2504, 2506, and / or 2508 can be modified.

[0332] In some embodiments, for a given application, controlling stray light and increasing the sensitivity of the lens assembly 2702 can be inversely related (e.g., blocking light beams can inversely affect the total amount of light received at the optical detector). Thus, in some implementations, it may be advantageous to design the lens assembly 2702 such that the baffle is configured to block or reduce the light at the image edge to about 0.1% of the amount of light incident on the optical detector at the center of the image (e.g., as described below in connection with Figure 22F and 22G ). In another implementation, alternatively or in combination, it may be advantageous to configure the lens assembly 2702 such that at least about 50% or at least about 60% of the light from the object is transmitted to the optical detector (e.g., as described below in connection with Figure 22GAlthough the lens assembly 2702 is described as including two baffles 2620 and 2630, it should be appreciated that the lens assembly 2702 can include any number of baffles suitable for vignetting an image at the optical detector for a suitable application.

[0333] Figure 22C is a front view schematic of the optical detector 2610 that depicts another example of optical crosstalk between adjacent optical channels and the potential resultant non-uniformity of the available image size due to the crosstalk. The detector 2610 can include a plurality of illumination regions 2616, each of which can correspond to an optical channel 2602 and associated components (such as lenses or lens elements 2504, 2506, 2508). For example, each illumination region 2616 can represent the region of the detector 2610 on which light incident on the first element of the associated optical channel 2602 impinges. In some embodiments, the width of the optical channels 2602 (such as lenses) at different locations can be less than the corresponding width of the illumination regions 2616. In Figure 22C the arrangement shown, the optical channels 2602 (including lenses of a lens array, for example) can be spaced apart in a two-dimensional array at generally uniform intervals. For example, the spacing between adjacent optical channels in the vertical direction can be approximately uniform, and the spacing between adjacent optical channels in the horizontal direction can also be approximately uniform.

[0334] Due to Figure 22C the spacing of the optical channels in, the illumination regions 2616 can overlap, as shown by the overlap regions 2618 in Figure 22C The overlap regions 2618 can occur because the images produced by the lenses in the illumination regions 2616 are typically larger than the corresponding regions of the associated lenses and other optical elements of the optical channels. The overlap regions 2618 can indicate optical crosstalk between adjacent optical channels and can introduce non-uniform image regions that reduce the effective size of the available image that is not contaminated by crosstalk from other channels. For example, Figure 22C depicts rectangular regions of different sizes, with the overlap regions 2618 disposed around each rectangular region. The rectangular regions can define the available image regions 2615 for imaging an object (such as a gas cloud).

[0335] For example, a first optical channel transmits light to a portion of the optical detector 2610 corresponding to the illumination region 2616A. Adjacent optical channels also transmit light within the corresponding illumination regions 2616B, 2616C, 2616D. However, because the optical channels are closely spaced together, at least the light in the illumination regions 2616B and 2616D can enter the adjacent illumination region 2616A, and vice versa. This results in Figure 22CMultiple overlapping areas 2618 are shown in .

[0336] exist Figure 22C In the illustrated arrangement, each optical channel 2602 also defines a detection area 2612 for the optical detector 2610. Each detection area 2612 comprises a square whose center can coincide with the optical axis or central axis through the lens assembly corresponding to the optical channel. The detection areas 2612 can include a plurality of pixels and can be spatially separated from one another. For example, in the illustrated arrangement, the detection areas 2612 can be separated by approximately 0.136 mm and can have dimensions of 4.25 mm by 4.25 mm. In some embodiments, the illumination area 2616 can have a diameter of 6.01 mm.

[0337] Thus, the illumination area 2616 of a particular channel can extend beyond the detection area 2612 of that channel and into the detection area 2612 of an adjacent channel, resulting in an overlap area 2618. Consequently, the overlap area 2618 can indicate optical crosstalk between the optical channels 2602. While specific example dimensions have been described above, these dimensions are not intended to be limiting and are merely one example of an optical detector 2610. For example, in the illustrated embodiment, the width or height of the detection area 2612 can be in the range of approximately 3 mm to approximately 6 mm, or in the range of 3.5 mm to 5 mm, such as approximately 4.250 mm. The height of the usable image area 2615 can be in the range of approximately 2 mm to 6 mm, such as 2 mm to 5 mm, or 2 mm to 4 mm. The width of the usable image area 2615 can be in the range of approximately 2 mm to 5 mm, such as 2 mm to 4 mm. However, the design of the lens assembly 2702 can be modified to provide a larger (or smaller) surface area for each usable area 2615.

[0338] like Figure 22CAs shown, in some arrangements, the available image area 2615 at the detector 2610 can be non-uniform. For example, for the illumination area 2616 (such as illumination area 2616A) in the inner area of the detector 2610, the overlapping area 2618 can reduce the available image area 2615A to a greater extent than the adjacent available image areas 2615B, 2615C, 2615D. That is, the image areas 2615B - 2615D can be larger than the image area 2615A. Additionally, the image area 2615C can be larger than the image areas 2615B, 2615D because the image area 2615C is set in the corner of the detector 2610 such that there is image overlap 2618 only on both sides of the detection area 2612. In contrast, the sizes of the image areas 2615B, 2615D are reduced due to the image overlap 2618 on three sides of the detection area 2612, and the size of the image area 2615A is reduced due to the image overlap 2618 on four sides of the detection area 2612.

[0339] Therefore, the different shapes and profiles of the image areas 2615A - 2615D result in a non-uniform image area at the detector 2610. In Figure 22C the arrangement, the maximum image size at the detector 2610 can be limited by the smallest available image area 2615 (e.g., the image area 2615A of the detector 2610) on the detector 2610. For example, in the shown arrangement, the available image area 2615A can be 162 pixels along the x direction and 162 pixels along the y direction, which can represent the maximum available area for imaging on the detector 2610. To improve the image quality and gas detection ability of the system 1000, it may be important to increase the available image area 2515 of the detector 2610.

[0340] Figure 22D Depicts an illumination area 2616 indicating light transmitted from an object to an optical detector, where the lens assembly can be configured to increase the available image area at the optical detector 2610 with reduced vignetting. Figure 22E Is a front view plan view of an example lens assembly 2702, the dimensions of which are designed to transmit radiation to Figure 22D the shown illumination area 2616. As with Figure 22C the arrangement, Figure 22D each illumination area 2616 can represent the area at the optical detector 2610 that receives light from a corresponding optical channel and associated lens. The illumination area 2616 can be larger than the corresponding lens in the optical channel 2602. As described above, due to the spacing of the optical channels 2602, the illumination areas 2616 overlap, as shown by the overlapping area 2618. The overlapping area 2618 can indicate optical crosstalk between adjacent optical channels. As with Figure 22CSimilarly, the overlapping region 2618 can define an available image region 2615, which is rectangular (e.g., approximately square) in Figure 22D . In the embodiment shown in Figure 22D , different from the embodiment shown in Figure 22C , these available image regions 2615 are approximately the same size, where more detection regions towards the center of the focal plane array are smaller than the detection regions at the periphery of the focal plane array.

[0341] In the embodiments of Figure 22D and 22E , compared to the arrangement of Figure 22C , the lens assembly 2702 can be designed to increase the available image region 2615. The optical properties and positions of the various optical elements in the lens assembly 2702 affect each other and affect the resulting available region 2615. For example, compared to the optical channels 2602 forming the available image region 2615 in Figure 22C , the optical channels 2602 (e.g., lenses 2504, 2506, 2508) in Figure 22E can be spaced farther apart. For example, the horizontal (center-to-center) spacing dx between adjacent lenses in the lens assembly 2702 can be in the range of 2 mm to 6 mm. The vertical (center-to-center) spacing dy between adjacent lenses in the lens assembly 2702 can be in the range of 2 mm to 6 mm. The horizontal spacing dx can be the same as or different from the vertical spacing dy. In some embodiments, the spacings dx, dy can be smaller near the center of the detector 2610 and can gradually increase near the edge of the detector 2610. Such an arrangement can shift the available image region 2615 farther away to reduce optical crosstalk and increase the area of each available region 2615. In other arrangements, the spacings dx, dy can be approximately uniform across the lens assembly 2702. In still other arrangements, the spacings dx, dy can be larger near the center of the detector 2610 and gradually decrease near the edge of the detector 2610, which can reduce optical crosstalk and / or increase the area of each available region 2615. Figure 22D The width of the available image region 2615 of Figure 22D can be in the range of 2.5 mm to 5 mm, in the range of 3 mm to 4 mm, in the range of 3 mm to 3.5 mm, e.g., approximately 3.357 millimeters. Figure 22D The height of the available image region 2615 of 2 can be in the range of 3 mm to 4 mm, e.g., approximately 3.523 mm. 2 The image region 2615 of 2 can be in the range of 9 mm 2 to 16 mm, or in the range of 9 mm

[0342] Additionally, the optical detector 2610 may include an effective imaging area 2610A that includes effective imaging elements or pixels for collecting image data from the IR radiation transmitted to the detector 2610. For example, the effective imaging area 2610A may include an area on the detector 2610 that includes effective pixels for sensing an image that is processed by the processing electronics to detect a target substance. In some embodiments, the effective imaging area 2610A may include all or substantially all of the area of the detector 2610. In other embodiments, the effective imaging area 2610A may be significantly less than the total area of the front face of the detector 2610. In Figure 22E the illustrated embodiment, the effective imaging area 2610A of the detector may include a total effective imaging area A I , A I may be defined by a horizontal width D x and a vertical height D y of the effective imaging area 2610A (e.g., A I = D x * D y ). Similarly, the lens assembly 2702 may define an optical coverage area A O representing an approximate lateral footprint of the lens assembly 2702. In the illustrated embodiment, the optical coverage area A O may be defined by a horizontal coverage L x and a vertical coverage L y of the lens assembly 2702 (e.g., A O = L x * L y ). The horizontal coverage L x may be defined based on the outermost lateral extent of the lens assembly 2702, as Figure 22E illustrated. Similarly, the vertical coverage L y may be defined based on the outermost vertical extent of the lens assembly 2702, as Figure 22E illustrated.

[0343] In Figure 22E embodiments, the optical coverage area A O may be larger than the effective imaging area A I . Additionally, the lens assembly 2702 may define N optical channels 2602, each channel 2602 imaging a beam or spot size area A b on the detector 2610 that may be slightly larger than the diameter or lateral dimension of the associated lens. In Figure 22E the spot size area A b is shown as coextensive with the optical channel 2602, but it should be appreciated that the spot size area Ab The total beam area A of the light impinging on the detector may be different due to diffraction, for example. T It can be calculated based on the portion of each beam or channel that illuminates the active area of the detector 2610. The total beam area A T Can be smaller than the effective imaging area A I In other words, there may be an active imaging area A I The area that does not receive light from the lens assembly 2702. The total beam area A T Can be smaller than the total effective imaging area A I In various embodiments, the total beam area A T Can be smaller than the total effective imaging area A I 95% of the total effective imaging area A I 90% or less than the total effective imaging area A I In some embodiments, the total beam area A T The total effective imaging area A I In the range of 50% to 98% of the total effective imaging area A I In the range of 55% to 75% of the total effective imaging area, or in the range of 57% to 67% of the total effective imaging area, for example, the total effective imaging area A I In some embodiments, the effective imaging area A I Can be smaller than the optical coverage area A O 98% of the optical coverage area A O 95% of the optical coverage area A O 90% of the optical coverage area A O 85% of the optical coverage area A O 80% or less than the optical coverage area A O In some embodiments, the effective imaging area A I The optical coverage area A O 50% to 98% of the optical coverage area A O 65% to 95% of the optical coverage area A O The range of 55% to 65% (e.g., about 62%).

[0344] exist Figure 22D and 22E In the embodiment shown, the optical channels are spaced such that the detector regions 2612 are spatially close together (e.g., approximately 0.136 mm apart in some embodiments), while also increasing or maximizing the size of the usable area 2615. Figure 22D and22E As shown, the optical channel 2602 can be configured so that the usable areas 2615 are spaced apart in a non-uniform spatial arrangement, but have a generally uniform size. For example, from a central usable area 2615A, the usable areas 2615 can be designed to be closer to one or more edges of its detector area 2612 and further away from adjacent usable areas 2615. Advantageously, Figure 22E The size design of the lens assembly 2702 in can increase the effective usable imaging area 2615 by reducing the overlap area 2618 and crosstalk.

[0345] For example, based on the location of each usable area 2615 and / or positioning of baffles 2620 and 2630 as described above, the usable area 2615 can have a width and length in the range of approximately 3 mm to 4 mm, e.g., as Figure 22D The embodiment shown has a width and length of approximately 3.523 mm by 3.357 mm. This can correspond to a number of available pixels within each available area 2615, for example, 207 pixels by 197 pixels, which is more than Figure 22C 2615 is approximately 55% larger. Although specific examples of usable area 2615 and lens assembly 2702 have been described herein, usable area 2615 and lens assembly 2702 may be modified and / or optimized for any suitable application. The above-described lens assembly 2702 is merely one embodiment, and the optical properties of the components within lens assembly 2702 may be modified as desired in conjunction with any other suitable type of imaging application.

[0346] In some embodiments, including may be based at least in part on Figure 22D The baffles 2620 and 2630 of the available area 2615 (as described above in conjunction with Figure 22B ) may be advantageous. For example, baffles 2620 and 2630 may be configured to allow light to be transmitted to optical detector 2610 within usable area 2615 while substantially blocking stray light that would otherwise be transmitted to the optical detector within overlap region 2618. In various embodiments, baffles 2620, 2630 may remove light in the overlap region such that the irradiance at or near the edge of the image area is near zero (or negligible). In various embodiments, the baffles may define the overlap region. For example, baffles 2620 and 2630 may be configured such that light is transmitted to optical detector 2610 within the usable area 2615 while substantially blocking stray light that would otherwise be transmitted to the optical detector within overlap region 2618. Figure 22D ) is relatively greater than the amount received at edge 2617B (see Figure 22D Thus, baffles 2620 and 2630 can be configured such that the relative intensity of light on usable area 2615 decreases with distance from center 2617A (e.g., as Figure 22F2617B) is a region of the optical system that is substantially independent of, or unaffected by, light passing between adjacent optical channels.

[0347] In various embodiments, the optical detector 2601 may include a detector array comprising a single FPA or an array of FPAs. In various embodiments, the optical detector 2601 may include a plurality of photosensitive devices. In some embodiments, the plurality of photosensitive devices may include a two-dimensional imaging sensor array that is sensitive to radiation having a wavelength between 1 μm and 20 μm (e.g., in the near infrared wavelength range, mid infrared wavelength range, or long infrared wavelength range). In various embodiments, the plurality of photosensitive devices may include CCD or CMOS sensors, bolometers, microbolometers, or other detectors sensitive to infrared radiation.

[0348] Although combined Figures 22B-22G A specific embodiment of lens assembly 2702 is described, but it should be appreciated that lens assembly 2702 can be designed for any suitable application. Lens assembly 2702 and the resulting usable area 2615 are one embodiment described in conjunction with various DAISI systems (e.g., the DAISI system can be mobile or fixed). However, the optical components and their positions within lens assembly 2702 (e.g., the number, size, and position of apertures and stops) can be modified as desired in conjunction with any other suitable type of imaging application. For example, lens assembly 2702 can be used with any suitable type of infrared imaging system or camera to control stray light to maintain the optical performance of the system. Based on the desired application, the lens assembly can be configured or optimized for any specific application with any desired components.

[0349] Figure 22F It is cross Figure 22D Example simulation of intensity roll-off for available area 2615. Figure 22FShows the relative illumination (e.g., intensity) at the optical detector 2610 as a function of the location on the available area 2615 (represented as line 2695). For example, the horizontal axis represents the position from the center 2617A in millimeters. The line 2695 can represent any line extending between the center 2617A and the edge 2617B (e.g., a position along a horizontal or vertical line or along a line at an angle thereto). In some embodiments, the line 2695 represents an intensity roll-off that vignettes the image at the optical detector 2610. In some embodiments, vignetting of the image can be caused by the baffles 2620 and / or 2630 in the lens assembly 2702. The simulation results can be obtained by optical simulation software (e.g., FRED TM software).

[0350] Figure 22F Illustrates that for the embodiments described above in connection with Figure 22D and 22E at the edge of the available area 2615, the light received drops to 0 relative to the maximum detected intensity or illumination. For example, at the center 2617A of the available area 2615A (position 0 millimeters on FIG. 2690), the amount of light received by the optical detector 2610. The amount of light can be normalized to provide a maximum value of 1.0 (or 100%). Although Figure 22F the example shown depicts a maximum value at the center 2617A, the normalization does not need to be at the center 2617A and can be at other locations on the available area 2615.

[0351] As described above, the simulation measures the amount of light received across the available area 2615 relative to the amount received at the center 2617A. Figure 22F Illustrates that the amount of light received at the edge 2617B can be reduced to approximately 0.01 (or 0.1%) of the light received at the center 2617A. The reduction of stray light at the edge 2617B can be based on implementing one or more of the baffles 2620 and / or 2630 and optimizing the lens assembly 2702, as described above in connection with Figure 22D and 22C For example, a figure of merit can be evaluated for various parameters of the lens assembly, including the following choices: the curvature of the lens surface, the position of the lens, the thickness of the lens, and the number, size, and position of the (one or more) apertures / (one or more) diaphragms, changing these parameters to determine a suitable design with appropriate vignetting. For example, the figure of merit can take into account its vignetting and / or effects. In some implementations, at least in part based on the baffles 2620 and / or 2630, stray light can be substantially blocked from passing between the optical channels.

[0352] Figure 22G Illustrates an example vignetting of an image of the scene 2720. Figure 22G shows the available area 2715 (represented as a square) of the simulation, and the available area 2715 is substantially similar to Figures 22D-22E the available area 2615. As Figure 22G shown, the image contained within the available area looks sharper and clearer, while the portion of the image 2720 outside the available area 2715 is darker. The darkening at the edges of the image 2720 indicates vignetting of the image to reduce or block the light received at the edges 2715b of the image without sacrificing the clarity or performance of the lens assembly 2702 at the center 2715a of the image 2720.

[0353] In the embodiments disclosed herein, the lenses or lens elements 2504, 2506, 2508 of the lens assembly 2702 (see Figure 18D herein) can be manufactured to meet precise tolerances, which can significantly improve the performance of the system 1000. The lens assemblies disclosed herein can be advantageously designed by selecting tolerances for each individual lens in the assembly and by selecting tolerances considering the lens assembly 2702 as a whole (e.g., by considering lens manufacturing errors, baffle size errors, etc.). For example, the embodiments disclosed herein can utilize one or more of the root sum square (RSS) and Monte Carlo techniques to select lens tolerances. The tolerances can be selected such that greater than or equal to 90% of the root mean square (rms) spot size is less than the diffraction-limited Airy disk of the imaging spot. This relatively conservative criterion can ensure improved system performance, which can also be manufactured according to the manufacturing techniques disclosed herein.

[0354] The lens assembly 2702 disclosed herein can be designed and manufactured to have a very low f-value (f / #) for each optical channel. The low f-value systems disclosed herein can advantageously significantly improve the sensitivity of the system (e.g., at least about 44%) for each optical channel. In some embodiments, for example, the lenses can be designed for the system 1000 to achieve f / 1 for each channel, where the focal length is approximately the same as the width of the effective system aperture. In various embodiments, the lens assembly 2702 can be designed to achieve an f-value in the range of f / 1 to f / 3, in the range of f / 1 to f / 2, in the range of f / 1 to f / 1.5, or in the range of f / 1 to f / 1.2. This low f-value can advantageously enable the detection of low concentrations of target substances such as methane. For example, at a wind speed of zero miles per hour (e.g., approximately very small or almost windless conditions), the sensitivity of the system 1000 disclosed herein to methane can be in the range of 0.00001 ft 3 / hr to 0.0006 ft 3 / hr, in the range of 0.00005 ft 3 / hr to 0.0006 ft3 within the range of / hr, at 0.00005 ft 3 / hr to 0.0004 ft 3 within the range of / hr, at 0.0001 ft 3 / hr to 0.0005 ft 3 within the range of / hr, at 0.0001 ft 3 / hr to 0.0004 ft 3 within the range of / hr, at 0.0002 ft 3 / hr to 0.0006 ft 3 within the range of / hr, or at 0.0002 ft 3 / hr to 0.0004 ft 3 / hr, the minimum flow rate or leakage rate within the range. As another example, at a wind speed of 15 mph, the sensitivity of the system 1000 disclosed herein to methane can be within the range of 0.01 ft 3 / hr to 0.3 ft 3 within the range of / hr, at 0.05 ft 3 / hr to 0.25 ft 3 within the range of / hr, at 0.1 ft 3 / hr to 0.25 ft 3 within the range of / hr, at 0.2 ft 3 / hr to 0.2 ft 3 within the range of / hr, or at 0.14 ft 3 / hr to 0.22 ft 3 / hr, the minimum flow rate or leakage rate within the range.

[0355] The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of methane to be in the range of 100 ppm-m to 400 ppm-m, in the range of 200 ppm-m to 300 ppm-m. For example, the minimum detection level is about 250 ppm-m, where ppm-m is provided in parts per million per meter. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of acetic acid to be in the range of 100 ppm-m to 200 ppm-m. For example, the minimum detection level is about 180 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of ammonia to be in the range of 5 ppm-m to 20 ppm-m. For example, the minimum detection level is about 13.5 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of benzene to be in the range of 100 ppm-m to 150 ppm-m. For example, the minimum detection level is about 125 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of butadiene to be in the range of 100 ppm-m to 150 ppm-m. For example, the minimum detection level is about 125 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of butane to be in the range of 200 ppm-m to 300 ppm-m. For example, the minimum detection level is about 250 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of carbon dioxide to be in the range of 1050 ppm-m to 1100 ppm-m. For example, the minimum detection level is about 1079 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of chlorobenzene to be in the range of 10 ppm-m to 40 ppm-m. For example, the minimum detection level is about 25 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of dichlorobenzene to be in the range of 25 ppm-m to 75 ppm-m. For example, the minimum detection level is about 50 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of 1,2-dichloroethane to be in the range of 100 ppm-m to 150 ppm-m. For example, the minimum detection level is about 125 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of ethane to be in the range of 200 ppm-m to 300 ppm-m. For example, the minimum detection level is about 250 ppm-m. The relatively low f-values provided by the embodiments disclosed herein can enable the minimum detection levels of ethanol to be in the range of 5 ppm-m to 25 ppm-m. For example, the minimum detection level is about 15 ppm-m.The relatively low f-values provided by the embodiments disclosed herein enable the minimum detection levels of ethylene to be in the range of 200 ppm-m to 300 ppm-m. Fo...

Claims

1. An optical system, comprising: An optical detector coupled to a base structure; A lens spaced apart from the optical detector along an axis, the lens being positioned to transmit light to the optical detector; A first thermal element mechanically and thermally coupled to a lateral connector and comprising a first material having a first coefficient of thermal expansion (CTE); A second thermal element mechanically and thermally coupled to the lateral connector and the lens, wherein the second thermal element comprises a second material having a second CTE, and wherein the second CTE is different from the first CTE; And A third thermal element mechanically and thermally coupled to the first thermal element and the base structure, wherein the third thermal element comprises a third material having a third CTE different from the first CTE; Wherein, in response to a temperature change, the respective lengths of the first thermal element, the second thermal element, and the third thermal element change to adjust the position of the lens relative to the optical detector along the axis, and wherein the second material comprises Delrin having a CTE of approximately 120 ppm / °C.

2. The optical system according to claim 1, wherein the focal length of the lens changes in response to the temperature change, and wherein in response to the temperature change, the respective lengths of the first thermal element and the second thermal element change to cause relative movement between the lens and the optical detector, thereby maintaining light transmission to the optical detector.

3. The optical system according to claim 2, wherein the temperature change comprises a temperature increase, and wherein in response to the temperature increase, the respective lengths of the first thermal element and the second thermal element change to move the lens closer to the optical detector, thereby maintaining light transmission to the optical detector.

4. The optical system according to claim 2, wherein the temperature change comprises a temperature decrease, and wherein in response to the temperature decrease, the respective lengths of the first thermal element and the second thermal element change to move the lens farther from the optical detector, thereby maintaining light transmission to the optical detector.

5. The optical system according to claim 1, further comprising: An outer housing structure mechanically and thermally coupled to the base structure, wherein the optical detector is disposed within the outer housing structure; And An optical window mechanically and thermally coupled to the outer housing structure.

6. The optical system according to claim 5, wherein the outer housing structure comprises kovar alloy, and the optical window comprises germanium.

7. The optical system according to claim 1, wherein the first material comprises aluminum.

8. The optical system according to claim 1, wherein the third material is the same as the first material.

9. The optical system according to claim 1, wherein the optical detector comprises an infrared focal plane array (FPA).

10. The optical system according to claim 1, wherein the second CTE is greater than the first CTE.

11. The optical system according to claim 1, wherein, When the optical system operates at any temperature within the range of -60°C to 100°C, the effective focal length of the lens changes by an amount within the range of 1 micron to 50 microns.

12. The optical system according to claim 1, wherein the lens comprises a plurality of lens elements.

13. The optical system according to claim 1, further comprising one or more optical filters disposed along the axis.

14. The optical system according to claim 1, wherein the optical detector is configured to detect infrared radiation.

15. The optical system according to claim 1, wherein the lens comprises germanium.

16. The optical system according to claim 1, wherein the optical system is configured to be worn by a person.

17. The optical system according to claim 1, wherein the first thermal element and the third thermal element are linearly coupled such that linear deformation of the first thermal element and the third thermal element causes the first thermal element and the third thermal element to deform in the same direction.

18. The optical system according to claim 1, wherein in response to the temperature change, the third thermal element and the first thermal element counteract a change in length of the second thermal element.

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