Alternating illumination for imaging systems and related methods and sorting systems

Abstract

Imaging systems and related methods and sorting systems are disclosed. An imaging system includes a plurality of sets of one or more illumination source and illumination control circuitry configured to operate the plurality of sets of one or more illumination sources with one or more first illumination sources turned on in a first time period, the one or more first illumination sources and one or more second illumination sources turned on in a second time period, and the one or more first illumination sources and one or more third illumination sources turned on in a third time period.

Description

TITLE ALTERNATING ILLUMINATION FOR IMAGING SYSTEMS AND RELATED METHODS AND SORTING SYSTEMS CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the filing date of Italian Utility Model Application No. 202023000004920, filed November 24, 2023, the disclosure of which is hereby incorporated herein in its entirety by this reference. FIELD

[0002] Embodiments of the present disclosure relate generally to illumination patterns for use in illumination systems and related sorting systems and methods. BACKGROUND

[0003] Multispectral imaging and hyperspectral imaging provide the ability to capture sub-images of a view or one or more targets viewed at different spectral bands. While hyperspectral imaging generally provides the ability to capture sub-images at a large number (e.g., hundreds) of narrow (e.g., 10 nm full width half maximum (FWHM)) spectral bands, the more recent development of multispectral imaging generally only provides the ability to capture sub-images at a smaller number (e.g., twenty or less) of spectral bands. While hyperspectral imaging generally provides more spectral information than multispectral imaging due to the larger number of monitored spectral bands, multispectral imaging is often used in place of hyperspectral imaging where high image acquisition rates or high image resolution is desired. BRIEF SUMMARY

[0004] In some embodiments, an imaging system includes one or more first illumination sources, one or more second illumination sources, one or more third illumination sources, and illumination control circuitry operably coupled to the one or more first illumination sources, the one or more second illumination sources, and the one or more third illumination sources, the illumination control circuitry configured to: control the one or more first illumination sources to emit first incident EM radiation toward a target and maintain the one or more second illumination sources and the one or more third illumination sources in an off state during a first time period, the first incident EM radiation having a first spectral band; control the one or more23205EPP first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a second time period, the second incident EM radiation having a second spectral band different from the first spectral band; and control the one or more first illumination sources and the one or more third illumination sources to emit the first incident EM radiation and third incident EM radiation, respectively, toward the target and maintain the one or more second illumination sources in the off state during a third time period, the third incident EM radiation having a third spectral band different from the first spectral band and the second spectral band.

[0005] In some embodiments, an imaging system further comprises an image sensor configured to: generate a first image signal responsive to first reflected EM radiation received responsive to the first incident EM radiation during the first time period; generate a second image signal responsive to the first reflected EM radiation and second reflected EM radiation received responsive to the second incident EM radiation during the second time period; and generate a third image signal responsive to the first reflected EM radiation and third reflected EM radiation received responsive to the third incident EM radiation during the third time period.

[0006] In some embodiments, an imaging system comprises signal processing circuitry configured to, responsive to the first image signal, the second image signal, and the third image signal, generate a first processed image signal proportional to the first reflected EM radiation, a second processed image signal proportional to the second reflected EM radiation, and a third processed image signal proportional to the third reflected EM radiation.

[0007] In some embodiments, an imaging system comprises signal processing circuitry configured to generate the first processed image signal by using the first image signal as the first processed image signal.

[0008] In some embodiments, an imaging system includes signal processing circuitry configured to generate the second processed image signal by subtracting the first image signal from the second image signal to obtain the second processed image signal.23205EPP

[0009] In some embodiments, an imaging system comprises signal processing circuitry configured to generate the third processed image signal by subtracting the first image signal from the third image signal to obtain the third processed image signal.

[0010] In some embodiments, an image system includes illumination control circuitry configured to repeatedly cycle through the first time period, the second time period, and the third time period.

[0011] In some embodiments, an imaging system includes illumination control circuitry configured to maintain the one or more first illumination sources emitting the first incident EM radiation through the repeated cycles through the first time period, the second time period, and the third time period.

[0012] In some embodiments, an imaging system includes illumination control circuitry configured to order the first time period, the second time period, and the third time period in sequence from the first time period to the second time period, and then to the third time period.

[0013] In some embodiments, an imaging system includes illumination control circuitry configured to order the first time period, the second time period, and the third time period in a sequence different from starting from the first time period, transitioning to the second time period, and then transitioning to the third time period.

[0014] In some embodiments, an imaging system further comprises one or more fourth illumination sources, wherein the illumination control circuitry is configured to control the one or more fourth illumination sources to emit fourth incident EM radiation toward the target during the first time period, the second time period, and the third time period, the fourth incident EM radiation having a fourth spectral band different from the first spectral band, the second spectral band, and the third spectral band.

[0015] In some embodiments, the first spectral band, the second spectral band, and the third spectral band are selected from an infrared spectral band and the fourth spectral band is a visible spectral band.

[0016] In some embodiments, an imaging system includes illumination control circuitry configured to: control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the23205EPP one or more third illumination sources in the off state during a fourth time period; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a fifth time period; and control the one or more first illumination sources and the one or more third illumination sources to emit the first incident EM radiation and the third incident EM radiation, respectively, toward the target and maintain the one or more second illumination sources in the off state during a sixth time period.

[0017] In some embodiments, an imaging system includes illumination control circuitry configured to: control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a subsequent time period subsequent to the third time period; and control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a time period immediately following the subsequent time period.

[0018] In some embodiments, a sorting system includes a plurality of sets of one or more illumination sources and illumination control circuitry configured to operate the plurality of sets of one or more illumination sources with one or more first illumination sources turned on in a first time period, the one or more first illumination sources and one or more second illumination sources turned on in a second time period, and the one or more first illumination sources and one or more third illumination sources turned on in a third time period.

[0019] In some embodiments, a sorting system further comprises an image sensor configured to capture a sub-image during each time period, wherein the illumination control circuitry is configured to repeatedly cycle through the first time period, the second time period, and the third time period and the image sensor is configured to capture a multispectral image each cycle through the first time period, the second time period, and the third time period.

[0020] In some embodiments, a sorting system includes illumination control circuitry configured to cycle back through the plurality of sets of one or more illumination sources from23205EPP a last of the plurality of sets of one or more illumination sources over multiple periods of time to a second set of the plurality of sets of one or more illumination sources then to only the one or more first illumination sources being maintained on.

[0021] In some embodiments, a sorting system further comprises an image sensor configured to capture a sub-image during each time period.

[0022] In some embodiments, a sorting system further comprises signal processing circuitry configured to generate processed image signals responsive to image signals captured during each time period, the processed image signals corresponding to individual spectral bands of each set of the plurality of sets of one or more illumination sources.

[0023] In some embodiments, a method of operating an imaging system comprises operating one or more first illumination sources in an on state during a first time period, capturing a first image signal in the first time period, operating the one or more first illumination sources and one or more second illumination sources in the on state during a second time period, capturing a second image signal in the second time period, operating the one or more first illumination sources and one or more subsequent illumination sources in the on state during a subsequent time period, and capturing a subsequent image signal in the subsequent time period. The method also includes generating a first processed image signal to be the first image signal, generating a second processed image signal to be the first image signal subtracted from the second image signal, and generating a subsequent processed image signal to be the first image signal subtracted from the subsequent image signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments of the invention / disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0025] FIG. 1 is a block diagram illustrating an imaging system, according to some embodiments;

[0026] FIG.2A through FIG.2E illustrate an example of stepped operation of the imaging system of FIG. 1;

[0027] FIG.3 is a flowchart illustrating a method 300 of operating an illumination system according to a step pattern, according to some embodiments;23205EPP

[0028] FIG.4 is a signal timing diagram of an example of illumination control signals that may be used in a stepped, zig-zag illumination pattern;

[0029] FIG. 5A through FIG. 5E illustrate an example of operation of the imaging system of FIG.1 in which one set of illumination sources is continuously on through the image capturing periods of time and the other sets of illumination sources are cycled through;

[0030] FIG. 6 is a flowchart illustrating a method of operating an imaging system according to a one set of illumination sources always on pattern, according to some embodiments;

[0031] FIG.7 is a signal timing diagram of an example of illumination control signals that may be used in a zig-zag illumination pattern in which one set of illumination sources is continuously on through the image capturing periods of time and the other sets of illumination sources are cycled through;

[0032] FIG. 8A through FIG. 8E illustrate an example of operation of the imaging system of FIG. 1 in which two sets of illumination sources are switched on at a time;

[0033] FIG. 9A illustrates an example of an implementation of a portion of the imaging system of FIG. 1 similar to the stepped example of FIG. 2A through FIG. 2E using four sets of illumination sources;

[0034] FIG. 9B is a signal timing diagram illustrating illumination control signals of FIG. 9A plotted against time;

[0035] FIG. 10A illustrates an example of an implementation of a portion of the imaging system of FIG. 1 similar to the one set of illumination sources continuously on example of FIG. 5A through FIG. 5E using four sets of illumination sources;

[0036] FIG. 10B is a signal timing diagram illustrating illumination control signals of FIG. 10A plotted against time;

[0037] FIG. 11 is a schematic representation of a sorter device according to some embodiments;

[0038] FIG.12 is a block diagram illustrating a portion of the computing device of FIG. 1, according to some embodiments;23205EPP

[0039] FIG.13 is a block diagram illustrating a portion of the computing device of FIG. 1, that may be used with the approach discussed in FIG. 10A and FIG. 10B; and

[0040] FIG. 14 is a schematic view of a computing device, according to some embodiments. DETAILED DESCRIPTION

[0041] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which are shown, by way of illustration, specific examples of embodiments in which the present disclosure may be practiced. These embodiments are described in sufficient detail to enable a person of ordinary skill in the art to practice the present disclosure. However, other embodiments enabled herein may be utilized, and structural, material, and process changes may be made without departing from the scope of the disclosure.

[0042] The illustrations presented herein are not meant to be actual views of any particular method, system, device, or structure, but are merely idealized representations that are employed to describe the embodiments of the present disclosure. In some instances, similar structures or components in the various drawings may retain the same or similar numbering for the convenience of the reader; however, the similarity in numbering does not necessarily mean that the structures or components are identical in size, composition, configuration, or any other property.

[0043] The following description may include examples to help enable one of ordinary skill in the art to practice the disclosed embodiments. The use of the terms "exemplary," "by example," and "for example," means that the related description is explanatory, and though the scope of the disclosure is intended to encompass the examples and legal equivalents, the use of such terms is not intended to limit the scope of an embodiment or this disclosure to the specified components, steps, features, functions, or the like.

[0044] It will be readily understood that the components of the embodiments as generally described herein and illustrated in the drawings could be arranged and designed in a wide variety of different configurations. Thus, the following description of various embodiments is not intended to limit the scope of the present disclosure, but is merely representative of23205EPP various embodiments. While the various aspects of the embodiments may be presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0045] Furthermore, specific implementations shown and described are only examples and should not be construed as the only way to implement the present disclosure unless specified otherwise herein. Elements, circuits, and functions may be shown in block diagram form in order not to obscure the present disclosure in unnecessary detail. Conversely, specific implementations shown and described are exemplary only and should not be construed as the only way to implement the present disclosure unless specified otherwise herein. Additionally, block definitions and partitioning of logic between various blocks is exemplary of a specific implementation. It will be readily apparent to one of ordinary skill in the art that the present disclosure may be practiced by numerous other partitioning solutions. For the most part, details concerning timing considerations and the like have been omitted where such details are not necessary to obtain a complete understanding of the present disclosure and are within the abilities of persons of ordinary skill in the relevant art.

[0046] Those of ordinary skill in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. Some drawings may illustrate signals as a single signal for clarity of presentation and description. It will be understood by a person of ordinary skill in the art that the signal may represent a bus of signals, wherein the bus may have a variety of bit widths and the present disclosure may be implemented on any number of data signals including a single data signal.

[0047] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a special purpose processor, a digital signal processor (DSP), an Integrated Circuit (IC), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general‑purpose processor (may also be referred to herein as a host processor or simply a host) may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP23205EPP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. A general-purpose computer including a processor is considered a special-purpose computer while the general-purpose computer is configured to execute computing instructions (e.g., software code) related to embodiments of the present disclosure.

[0048] The embodiments may be described in terms of a process that is depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe operational acts as a sequential process, many of these acts can be performed in another sequence, in parallel, or substantially concurrently. In addition, the order of the acts may be re-arranged. A process may correspond to a method, a thread, a function, a procedure, a subroutine, a subprogram, other structure, or combinations thereof. Furthermore, the methods disclosed herein may be implemented in hardware, software, or both. If implemented in software, the functions may be stored or transmitted as one or more instructions or code on computer-readable media. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another.

[0049] Any reference to an element herein using a designation such as "first," "second," and so forth does not limit the quantity or order of those elements, unless such limitation is explicitly stated. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be employed there or that the first element must precede the second element in some manner. In addition, unless stated otherwise, a set of elements may include one or more elements.

[0050] As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as, for example, within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90% met, at least 95% met, or even at least 99% met.23205EPP

[0051] Multispectral imaging may be preferred over hyperspectral imaging in applications where high image acquisition rate is desirable, especially where relatively few separate spectral bands are of interest. In high-acquisition rate multispectral imaging, a design tradeoff exists between the number of separate spectral bands tracked and the acquisition rate because illuminating and capturing a larger number of images takes more time than illuminating and capturing a smaller number of images. This tradeoff between the number of tracked spectral bands and acquisition rate may motivate designers of multispectral imaging systems for high acquisition rate applications to reduce (e.g., minimize) the number of tracked spectral bands.

[0052] Control over which spectral band is being imaged for may be exerted at the image sensor (e.g., using bandpass filters), at the illumination sources (e.g., using illumination sources that emit incident electromagnetic (EM) radiation at specific spectral bands), or both. The switching on and off of illumination sources such as light emitting diodes (LEDs) at targeted spectral bands is generally faster than modulation of variable bandpass filters (e.g., color wheels, electrically controllable optical bandpass filters). Accordingly, controlling the spectral band at the illumination sources may be better suited for high acquisition rate multispectral imaging than controlling the spectral band at the image sensor.

[0053] One way to implement control over the spectral band at the illumination sources may involve sequentially controlling illumination sources having different spectral bands to emit incident EM radiation one at a time during separate time intervals. Images may be captured using an image sensor (e.g., a camera) at each of the separate time intervals to effectively obtain a separate image illuminated by each separate spectral band. For example, one or more first illumination sources emitting incident EM radiation at a first spectral band may be turned on during a first time period while other illumination sources are turned off. An image may be captured during the first time period. One or more second illumination sources emitting EM radiation at a second spectral band different from the first spectral band may be turned on during a second time period while other illumination sources are turned off. An image may be captured during the second time period. This may be continued with illumination sources of other spectral bands until an image corresponding to each spectral band has been captured, and some or all of the resulting images may be analyzed as a multispectral image.23205EPP

[0054] Sequentially illuminating with separate spectral bands during separate time periods may be an effective way to modulate spectral bands for purposes of high-acquisition rate multispectral imaging applications. A similar effect, however, may be obtained by strategically illuminating using one, and sometimes more than one, spectral band and separating the individual spectral bands from each other using signal processing. Doing so may result in reduced switching time between different image acquisition time periods because in some instances illumination sources may be left on from one image acquisition time period to another, eliminating a “turn off” operation between image acquisition time periods. Although this may amount to a small time gain in isolation, where a very large number of cycles of capturing a multispectral image is repeated, non-trivial time gains may be achieved in some instances.

[0055] FIG. 1 is a block diagram illustrating an imaging system 100, according to some embodiments. The imaging system 100 of FIG. 1 includes multiple sets of one or more illumination sources configured to emit incident EM radiation in respective different spectral bands. For example, the imaging system 100 includes one or more first illumination sources 106 configured to emit first incident EM radiation 124 of a first spectral band Δλ1 at least partially toward a target 104. The imaging system 100 also includes one or more second illumination sources 108 configured to emit second incident EM radiation 126 of a second spectral band Δλ2 at least partially toward the target 104. The second spectral band Δλ2 is different from the first spectral band Δλ1. The imaging system 100 further includes one or more third illumination sources 110 configured to emit third incident EM radiation 128 of a third spectral band Δλ3 at least partially toward the target 104. The third spectral band Δλ3 is different from the first spectral band Δλ1 and the second spectral band Δλ2.

[0056] The imaging system 100 includes a computing device 112 to control the imaging system 100. The computing device 112 includes illumination control circuitry 130, signal processing circuitry 118, and one or more data storage devices 114. The illumination control circuitry 130 is operably coupled to the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110. The illumination control circuitry 130 is configured to selectively control the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more23205EPP third illumination sources 110 to turn on and off during different image acquisition time periods according to desired image acquisition patterns. By way of non-limiting example, the illumination control circuitry 130 is configured to provide illumination control signals 132 to the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 to control switching on and off. As a result, images captured during these different image acquisition time periods may be illuminated by one or more spectral bands, as controlled by the illumination control circuitry 130.

[0057] The imaging system 100 includes an image sensor 102 configured to generate an image signal 140 responsive to one or more received first reflected EM radiation 134, second reflected EM radiation 136, and third reflected EM radiation 138 during each image acquisition time period. The image sensor 102 provides the image signal 140 to the computing device 112, which may store image signals 120 using the one or more data storage devices 114.

[0058] The signal processing circuitry 118 is configured to extract, responsive to the image signals 120 stored by the one or more data storage devices 114, processed signals 122 corresponding to the individual spectral bands Δλ1, Δλ2, Δλ3. By way of non-limiting example, the processed signals 122 include a first processed signal corresponding to the first spectral band Δλ1, a second processed signal corresponding to the second spectral band Δλ2, and a third processed signal corresponding to the third spectral band Δλ3.

[0059] For the sake of simplicity of the disclosure, only three sets of one or more illumination sources are shown in FIG. 1. Some embodiments disclosed herein are discussed with reference to this example of three sets of illumination sources. A person of ordinary skill in the art, however, would be able to, based on this disclosure, extend the embodiments disclosed herein to examples where more than three sets of one or more illumination sources are used. Accordingly, the examples and embodiments disclosed herein contemplate use in systems where more than three sets of one or more illumination sources are used.

[0060] FIG.2A through FIG.2E illustrate an example of stepped operation of the imaging system 100 of FIG. 1. In this example, the sets of illumination sources (e.g., the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG.1) may be turned on one at a time and left on as the next set of illumination sources is turned on. An image signal may be captured (e.g., using the23205EPP image sensor 102 of FIG. 1) as each set of illumination sources is turned on, and signal processing may be performed on the image signals to separate the individual spectral bands (e.g., Δλ1, Δλ2, and Δλ3of FIG. 1) corresponding to the sets of illumination sources from the image signals 120. Specifically, the first image signal may be taken as the first processed image signal, and each subsequent processed image signal may be the current image signal minus the previous image signal. As a result, a multispectral image including sub-images corresponding to the individual spectral bands may be obtained.

[0061] FIG. 2A is a portion of the imaging system 100 of FIG. 1 to illustrate illumination control signals 132 that may be used in this example of stepped operation. FIG. 2A illustrates the illumination control circuitry 130, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG. 1. FIG. 2A also illustrates the illumination control signals 132 of FIG. 1, which in this example include a first illumination control signal 208 (shown using an arrow with a solid line), a second illumination control signal 210 (shown using an arrow with a dashed line), and a third illumination control signal 212 (shown using an arrow with a dotted line).

[0062] The illumination control circuitry 130 is configured to selectively and separately control each of the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 using the first illumination control signal 208, the second illumination control signal 210, and the third illumination control signal 212, respectively.

[0063] FIG. 2B is a signal timing diagram illustrating the illumination control signals 132 of FIG. 2A plotted against time. The signal timing diagram includes separate plots for first illumination control signal 208 (used for controlling the one or more first illumination sources 106 of FIG. 2A), second illumination control signal 210 (used for controlling the one or more second illumination sources 108 of FIG. 2A), and third illumination control signal 212 (used for controlling the one or more third illumination sources 110 of FIG. 2A). The vertical axes for these plots are volts and the horizontal axes for these plots are units of time.

[0064] The plots in FIG. 2B include two cycles of three time periods Δt1, Δt2, and Δt3. Where the number of sets of illumination sources is greater than three, however, the number23205EPP of time periods in each cycle would be greater than three. Only three time periods are illustrated in FIG. 2B in each cycle for ease of the disclosure.

[0065] Referring to FIG.2A and FIG.2B together, during a first image capture time period Δt1(also referred to herein simply as “first time period Δt1”) from a first time t1to a second time t2, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and maintains turned off the one or more second illumination sources 108 and the one or more third illumination sources 110. As illustrated in FIG. 2B, the illumination control circuitry 130 maintains the first illumination control signal 208 at a logic level high voltage potential corresponding to a sufficiently high voltage potential to maintain the one or more first illumination sources 106 on during the first time period Δt1. As also illustrated in FIG. 2B, the illumination control circuitry 130 maintains the second illumination control signal 210 and the third illumination control signal 212 at a logic level low voltage potential to maintain the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state.

[0066] FIG. 2C illustrates the imaging system 100 of FIG. 1 during the first time period Δt1. As illustrated in FIG.2C, the illumination control circuitry 130 controls the one or more first illumination sources 106 to emit first incident EM radiation 124 toward the target 104 and maintains the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state during the first time period Δt1. The first incident EM radiation has a first spectral band Δλ1. Responsive to the first incident EM radiation 124, the image sensor 102 receives first reflected EM radiation 134, which likewise has the first spectral band Δλ1.

[0067] The image sensor 102 is configured to generate a first image signal 218 responsive to the first reflected EM radiation 134, which is, as discussed above, received responsive to the first incident EM radiation 124 during the first time period Δt1. The image sensor 102 may include an array of detector elements (e.g., a one-dimensional or a two-dimensional array of detector elements) corresponding to image pixels (e.g., a one-dimensional or a two-dimensional array of image pixels). At each of these detector elements, the image sensor 102 may measure an EM field and generate a corresponding electrical signal proportional to the measured EM field. represents a matrix of EM field values at the detector elements of the detector23205EPP array of the image sensor 102 during the first time period Δt1. Accordingly, the first image signal 218 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor: , where indicates “is proportional to.”

[0068] Since the only incident EM radiation during the first time period Δt1 is the first incident EM radiation 124, the spectral band of the electric field values at image sensor 102 is the first spectral band Δλ1. The first image signal 218, to the firstspectral band Δλ1. The image sensor 102 provides the first image signal 218 ( ) to thecomputing device 112, which stores the first image signal 218 to the one or more data storage devices 114 (e.g., in image signals 120).

[0069] Since the first image signal 218 is proportional to the electric field values for the first spectral band Δλ1alone, the signal processing circuitry 118 may storea first image signal 220 ( ) equal to the first image signal 218 ( ) to the one ormore data storage devices 114 in processed signals 122:

[0070] With reference to FIG. 2A and FIG. 2B together, during a second image capture time period Δt2(also referred to herein simply as “second time period Δt2”) from a second time t2to a third time t3, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106, turns on and maintains turned on the one or more second illumination sources 108, and maintains turned off the one or more third illumination sources 110. As illustrated in FIG. 2B, the illumination control circuitry 130 maintains the first illumination control signal 208 and the second illumination control signal 210 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 and the one or more second illumination sources 108 on during the second time period Δt2. As also illustrated in FIG. 2B, the illumination control23205EPP circuitry 130 maintains the third illumination control signal 212 at a logic level low voltage potential to maintain the one or more third illumination sources 110 in an off state.

[0071] FIG.2D illustrates the imaging system 100 of FIG.1 during the second time period Δt2. As illustrated in FIG.2D, the illumination control circuitry 130 controls the one or more first illumination sources 106 and the one or more second illumination sources 108 to emit first incident EM radiation 124 and second incident EM radiation 126, respectively, toward the target 104 and maintains the one or more third illumination sources 110 in an off state during the second time period Δt2. The first incident EM radiation has a first spectral band Δλ1 and the second incident EM radiation 126 has a second spectral band Δλ2. Responsive to the first incident EM radiation 124 and the second incident EM radiation 126, the image sensor 102 receives first reflected EM radiation 134 and second reflected EM radiation 136, which likewise have the first spectral band Δλ1 and the second spectral band Δλ2, respectively.

[0072] The image sensor 102 is configured to generate a second image signal 222 responsive to the first reflected EM radiation 134 and the second reflected EM radiation 136, which are, as discussed above, received responsive to the first incident EM radiation 124 and the second incident EM radiation 126 during the second time period Δt2. The image sensor 102 may measure, at each of the detector elements, an EM field and generate a corresponding electrical signal proportional to the measured EM field. Since EM radiation interferes linearly, the electric field at each of the detector elements is the sum of the electric field responsive to first incident EM radiation 124 alone and the electric field responsive to second incident EM radiation 126 alone. Accordingly, the sum represents a matrix of EM field values at the detector elements of the detectorsensor 102 during the second time period Δt2. Accordingly, the second image signal 222 may include a matrix of electrical signal values , which is proportional to the electric field values at the image.

[0073] Since the incident EMsecond time period Δt2includes both the first incident EM radiation 124 and the second incident EM radiation 126, the spectral band of the electric field values at image sensor 102 includes both the first spectral23205EPP band Δλ1and the second spectral band Δλ2. The image sensor 102 provides the second imagesignal 222 ( ) to the computing device 112, which stores the second image signal 222 to theone or storage devices 114 in image signals 120.

[0074] Since the second image signal 222 is proportional to the sum of electric field values for the first spectral band Δλ1and the second spectral band Δλ2, the signal may generate a second processed image signal 224 by subtracting thefirst ) (stored in the one or more data storage devices 114 at image signals120) from the second signal 222 ( ):, which is proportional to minus , or equivalently, proportional to :.The signal processing circuitry 118 isthe second processed image signal 224( ) equal to the second image signal 222 ( ) minus the first image signal 218 ( ) to theone or more data storage devices 114 in the processed signals 122:.

[0075] With reference toduring a third image capture time period Δt3(also referred to herein simply as “third time period Δt3”) starting at a third time t3, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more second illumination sources 108 and turns on and maintains turned on the one or more third illumination sources 110. As illustrated in FIG. 2B, the illumination control circuitry 130 maintains the first illumination control signal 208, the second illumination control signal 210, and the third illumination control signal 212 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 on during the 3rd time period Δt3.23205EPP

[0076] FIG. 2E illustrates the imaging system 100 of FIG. 1 during the third time period Δt3. As illustrated in FIG.2E, the illumination control circuitry 130 controls the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 to emit first incident EM radiation 124, second incident EM radiation 126, and third incident EM radiation 128, respectively, toward the target 104 during the third time period Δt3. The first incident EM radiation has a first spectral band Δλ1, the second incident EM radiation 126 has a second spectral band Δλ2, and the third incident EM radiation 128 has a third spectral band Δλ3. Responsive to the first incident EM radiation 124, the second incident EM radiation 126, and the third incident EM radiation 128, the image sensor 102 receives first reflected EM radiation 134, second reflected EM radiation 136, and third reflected EM radiation 138, which likewise have the first spectral band Δλ1, the second spectral band Δλ2, and the third spectral band Δλ3, respectively.

[0077] The image sensor 102 is configured to generate a third image signal 226 responsive to the first reflected EM radiation 134, the second reflected EM radiation 136, and the third reflected EM radiation 138, which are, as discussed above, received responsive to the first incident EM radiation 124, the second incident EM radiation 126, and the third incident EM radiation 128 during the third time period Δt3. The image sensor 102 may measure, at each of the detector elements, an EM field and generate a corresponding electrical signal proportional to the measured EM field. Since EM radiation interferes linearly, the electric field at each of the detector elements is the sum of the electric field responsive to first incident EM radiation 124 alone with the electric field responsive to second incident EM radiation 126 alone and the electric field responsive to third incident EM radiation 128 alone. Accordingly, the sum represents a matrix of EM field values at the detector elements of thesensor 102 during the third time period Δt3. As a result, the third image signal 226 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor: .

[0078] Since the incidenttime period Δt3includes the first incident EM radiation 124, the second incident EM radiation 126, and the third incident EM23205EPP radiation 128, the spectral band of the electric field values at image sensor 102 includes the first spectral band Δλ1, the second spectral band Δλ2, and the thirdspectral band Δλ3. The image sensor 102 provides the third image signal 226 ( ) to thecomputing device 114, which stores the third image signal 226 to the one or storagedevices 114 in image signals 120.

[0079] Since the third image signal 226 is proportional to the sum of electric field values for the first spectral band Δλ1, the second spectral band Δλ2, the signal processing circuitry 118 may generate a thirdprocessed image signal 228 by subtracting the immediately previous image signal ( ) (storedin the one or more data storage devices 114 at image signals 120) from the signal226 ( ):, which is proportional to, or equivalently, proportional to : .

[0080] The signal processingto store the third processedimage signal 228 ( ) equal to the third image signal 226 ( ) minus the second image signal222 ( ) to themore data storage devices 114 in processed signals 122:.

[0081] To generalize theillustrated in FIG.2A through FIG.2E for an arbitrary number N of sets of one or more illumination sources, the following maybe used to obtain processed signals 122 ( , , … ):.23205EPP

[0082] Since the illumination control circuitry 130 does not turn off sets of illumination sources between every one of the transitions between the time periods Δt1, Δt2, Δt3, these time periods may be slightly shorter than in a scenario where the illumination control circuitry 130 was turning off sets of illumination sources between each time period. As a result, the example illustrated in FIG.2A through FIG.2E may cycle through time periods relatively faster compared to systems where sets of illumination sources are switched off between each time period. Accordingly, the example illustrated in FIG. 2A through FIG. 2E may enable a faster image acquisition rate.

[0083] Although the time periods are discussed in order from the first time period Δt1 to the third time period Δt3, the time periods may instead be cycled through in any other order. If the image signals are saved in image signals 120 of the one or more data storage devices 114, the signal processing circuitry 118 may generate the processed signals 122 from the image signals 120 regardless of the order in which the time periods are cycled through. Accordingly, in some embodiments, the illumination control circuitry 130 is configured to order the first time period, the second time period, and the third time period in sequence from the first time period to the second time period, and then to third time period. Also, in some embodiments, the illumination control circuitry 130 is configured to order the first time period, the second time period, and the third time period in a sequence different from starting from the first time period, transitioning to the second time period, and then transitioning to the third time period.

[0084] FIG.3 is a flowchart illustrating a method 300 of operating an illumination system according to a step pattern, according to some embodiments. At operation 302, method 300 includes operating one or more first illumination sources in an on state during a first time period. At operation 304, method 300 includes capturing a first image signal in the first time period. At operation 306, method 300 includes operating the one or more first illumination sources and one or more second illumination sources in the on state during a second time period. At operation 308, method 300 includes capturing a second image signal in the second time period. At operation 310, method 300 includes operating the one or more first illumination sources, the one or more second illumination sources, and one or more subsequent illumination sources in the on state during a subsequent time period. At operation 312, method 300 includes capturing a subsequent image signal in the subsequent time period. At operation 314, method23205EPP 300 includes generating a first processed image signal to be the first image signal. At operation 316, method 300 includes generating a second processed image signal to be the first image signal subtracted from the second image signal. At operation 318, method 300 includes generating a subsequent processed image signal to be an immediately previous image signal previous to the subsequent image signal subtracted from the subsequent image signal.

[0085] FIG.4 is a signal timing diagram of an example of illumination control signals 132 that may be used in a stepped, zig-zag illumination pattern. The illumination control signals 132 in this example include a first illumination control signal 402, a second illumination control signal 404, and a third illumination control signal 406, which may be provided by the illumination control circuitry 130 of FIG. 1 to control the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG.1. In a first three time periods, Δt1, Δt2, and Δt3, the first illumination control signal 402, the second illumination control signal 404, and the third illumination control signal 406 may be controlled similarly to the first illumination control signal 208, the second illumination control signal 210, and the third illumination control signal 212 of FIG. 2B to capture a first image signal , a second image signal , and a third image signal in the first time period Δt1, the second time period Δt2, and the third time periodΔt3, respectively, similar to the first image signal 218 ( ), the second image signal 222 ( ),and the third image signal 226 ( ) acquired asabove with reference to FIG. 2Athrough FIG. 2E.

[0086] Processed signals , , and corresponding to a first multispectral image 408 may be generatedthe signal processing circuitry 118 of FIG. 1) responsive to first image signal , second image signal , and third image signal in a similar manner as discussed with reference to FIG.2A through FIG.2E for generating the first processed signal , the second processed signal , and the third processed signal responsive tothe first image signal 218 ( ), the second image signal 222 ( ), and the third image signal226 ( ). The processed signals , , andbe stored in the processed23205EPP signals 122 of the one or more data storage devices 114 of FIG. 1. For example, the processed signals , , and may be determined as:.

[0087] At a fourth time control circuitry 130 (FIG. 1)maintains the first illumination control signal 402 and the second illumination control signal 404 at logic level high voltage potentials that are sufficiently high to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 (FIG. 1) in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 406 at a logic level low voltage potential to operate the one or more third illumination sources 110 in an off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG. 1).

[0088] At a fifth time period Δt5, the illumination control circuitry 130 (FIG.1) maintains the first illumination control signal 402 at a logic level high voltage potential to operate the one or more first illumination sources 106 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 404 and the third illumination control signal 406 at logic level low voltage potentials to operate the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 or more data storage devices 114 of FIG. 1).

[0089] Processed signals , , and corresponding to a second multispectral image 410 may beprocessing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more data storage devices 114 of example, processed signals , , and may be determined to be:23205EPP .

[0090] At a sixth time circuitry 130 (FIG.1) maintainsthe first illumination control signal 402 and the second illumination control signal 404 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 406 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 one or more data storage devices 114 of FIG. 1).

[0091] At a seventh time period Δt7, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 402, the second illumination control signal 404, and the third illumination control signal 406 at logic level high voltage potentials to operate the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 in a turned on state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signalsof the one or more data storage devices 114 of FIG. 1).

[0092] Processed signals , , and corresponding to a third multispectral image 412 may be generated (e.g.,processing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more data114 of FIG. 1. For example, processed signals , , and may be determined to be:.23205EPP

[0093] At an eighth time period Δt8, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 402 and the second illumination control signal 404 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 406 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signalsone or more data storage devices 114 of FIG.1).

[0094] At a ninth time period Δt9, the illumination control circuitry 130 (FIG.1) maintains the first illumination control signal 402 at a logic level high voltage potential to operate the one or more first illumination sources 106 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 404 and the third illumination control signal 406 at logic level low voltage potentials to operate the one or more second illumination sources 108 and the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG. 1).

[0095] Processed signals , , and corresponding to a fourth multispectral image 414 may beprocessing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more data114 of example, processed signals , , and may be determined to be:.

[0096] At a tenth time period Δt10, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 402 and the second illumination control signal 404 at logic level high voltage potentials to operate the one or more first illumination sources 10623205EPP and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 406 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals one or more data storage devices 114 of FIG.1).

[0097] At an eleventh time period Δt11, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 402, the second illumination control signal 404, and the third illumination control signal 406 at logic level high voltage potentials to operate the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 in a turned on state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals theone or more data storage devices 114 of FIG. 1).

[0098] Processed signals , , and corresponding to a fifth multispectral image 416 may be generatedcircuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more dataFor example, processed signals , , and may be determined to be: .

[0099] At a twelfth timecontrol circuitry 130 (FIG. 1) maintains the first illumination control signal 402 and the second illumination control signal 404 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 406 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state.23205EPP An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG.1).

[0100] At a thirteenth time period Δt13, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 402 at a logic level high voltage potential to operate the one or more first illumination sources 106 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 404 and the third illumination control signal 406 at logic level low voltage potentials to operate the one or more second illumination sources 108 and the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG. 1).

[0101] Processed signals , , and corresponding to a sixth multispectral image 418 may be generated (e.g., byprocessing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more dataFor example, processed signals , , and may be determined to be:.

[0102] In this example, sixincluding three processed signals corresponding to three different spectral bands, were generated over thirteen time periods. By comparison, the example illustrated in FIG.2A through FIG.2E would take eighteen time periods to generate six multispectral images including three processed signals each. Accordingly, the zig-zag step illumination pattern illustrated in FIG.4 results in a faster effective acquisition rate for multispectral images as compared to the stepped illumination pattern of FIG. 2A through FIG. 2E. Where three sets of one or more illumination sources are used, the zig-zag step illumination pattern of FIG. 4 results in about a 33% faster effective acquisition rate for multispectral images than the step illumination example of FIG.2A through FIG.2E. Where four23205EPP sets of one or more illumination sources are used, the zig-zag step illumination pattern of FIG. 4 result in about a 25% faster effective acquisition rate of multispectral images than the step illumination example of FIG. 2A through FIG. 2E. Where five sets of one or more illumination sources are used, the zig-zag step illumination pattern of FIG. 4 result in about a 20% faster effective acquisition rate of multispectral images than the sept illumination example of FIG. 2A through FIG. 2E.

[0103] FIG. 5A through FIG. 5E illustrate an example of operation of the imaging system 100 of FIG. 1 in which one set of illumination sources is continuously on through the image capturing periods of time and the other sets of illumination sources are cycled through. In this example, a first image signal may be captured (e.g., using image sensor 102 of FIG. 1) with just the first continuously on set on, and an image signal may be captured (e.g., using the image sensor 102 of FIG. 1) as each set of illumination sources is turned on together with the always on set. Signal processing may be performed on the image signals to separate the individual spectral bands (e.g., Δλ1, Δλ2, and Δλ3 of FIG. 1) corresponding to the sets of illumination sources. Specifically, the first image signal may be taken as the first processed image signal, and each subsequent processed image signal may be the current image signal minus the first image signal. As a result, a multispectral image including sub-images corresponding to the individual spectral bands may be obtained.

[0104] FIG. 5A is a portion of the imaging system 100 of FIG. 1 to illustrate illumination control signals 132 that may be used in this example of stepped operation. FIG. 5A illustrates the illumination control circuitry 130, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG. 1. FIG. 5A also illustrates the illumination control signals 132 of FIG. 1, which in this example include a first illumination control signal 508 (shown using an arrow with a solid line), a second illumination control signal 510 (shown using an arrow with a dashed line), and a third illumination control signal 512 (shown using an arrow with a dotted line).

[0105] The illumination control circuitry 130 is configured to selectively and separately control each of the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 using the first23205EPP illumination control signal 508, the second illumination control signal 510, and the third illumination control signal 512, respectively.

[0106] FIG. 5B is a signal timing diagram illustrating the illumination control signals 132 of FIG. 5A plotted against time. The signal timing diagram includes separate plots for first illumination control signal 508, which is used for controlling the one or more first illumination sources 106 of FIG. 5A, second illumination control signal 510, which is used for controlling the one or more second illumination sources 108 of FIG. 5A, and third illumination control signal 512, which is used for controlling the one or more third illumination sources 110 of FIG.5A. The vertical axes for these plots are volts and the horizontal axes for these plots are units of time.

[0107] The plots in FIG. 5B include two cycles of three time periods Δt1, Δt2, and Δt3. Where the number of sets of illumination sources is greater than three, however, the number of time periods in each cycle would be greater than three, and only three time periods are illustrated in FIG.5B in each cycle for ease of the disclosure.

[0108] Referring to FIG. 5A and FIG. 5B together, during a first time period Δt1 from a first time t1 to a second time t2, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and maintains turned off the one or more second illumination sources 108 and the one or more third illumination sources 110. As illustrated in FIG.5B, the illumination control circuitry 130 maintains the first illumination control signal 508 at a logic level high voltage potential corresponding to a sufficiently high voltage potential to maintain the one or more first illumination sources 106 on during the first time period Δt1. As also illustrated in FIG. 5B, the illumination control circuitry 130 maintains the second illumination control signal 510 and the third illumination control signal 512 at a logic level low voltage potential to maintain the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state.

[0109] FIG. 5C illustrates the imaging system 100 of FIG. 1 during the first time period Δt1. As illustrated in FIG.5C, the illumination control circuitry 130 controls the one or more first illumination sources 106 to emit first incident EM radiation 124 toward the target 104 and maintains the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state during the first time period Δt1. The first incident EM radiation has a first spectral band Δλ1. Responsive to the first incident EM radiation 124, the23205EPP image sensor 102 receives first reflected EM radiation 134, which likewise has the first spectral band Δλ1.

[0110] The image sensor 102 is configured to generate a first image signal 518 responsive to the first reflected EM radiation 134, which is, as discussed above, received responsive to the first incident EM radiation 124 during the first time period Δt1. At each of the detector elements of the image sensor 102, the image sensor 102 may measure an EM field and generate a corresponding electrical signal proportional to the measured EM field. represents a matrix of EM field values at the detector elements of the detector image sensor102 during the first time period Δt1. Accordingly, the first image signal 518 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor:.

[0111] Since the only incidentduring the first time period Δt1 is the first incident EM radiation 124, the spectral band of the electric field values at image sensor 102 is the first spectral band Δλ1. The first image signal 518,to the firstspectral band Δλ1. The image sensor 102 provides the first image signal 518 ( ) to thecomputing device 112, which stores the first image signal 518 to the one orstorage devices 114 (e.g., in image signals 120).

[0112] Since the first image signal 518 is proportional to the electric field values for the first spectral band Δλ1 alone, the signal processing circuitry 118 may storea first image signal 520 ( ) equal to the first image signal 518 ( ) to the one ormore data storage devices 114 in processed signals 122:.

[0113] With reference toduring a second image capture time period Δt2 (also referred to herein simply as “second time period Δt2”) from a second time t2 to a third time t3, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106, turns on the one or more second illumination sources 108, and maintains turned off the one or more third illumination sources 110. As illustrated in FIG. 5B,23205EPP the illumination control circuitry 130 maintains the first illumination control signal 508 and the second illumination control signal 510 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 and the one or more second illumination sources 108 on during the second time period Δt2. As also illustrated in FIG.5B, the illumination control circuitry 130 maintains the third illumination control signal 512 at a logic level low voltage potential to maintain the one or more third illumination sources 110 in an off state.

[0114] FIG.5D illustrates the imaging system 100 of FIG.1 during the second time period Δt2. As illustrated in FIG.5D, the illumination control circuitry 130 controls the one or more first illumination sources 106 and the one or more second illumination sources 108 to emit first incident EM radiation 124 and second incident EM radiation 126, respectively, toward the target 104 and maintains the one or more third illumination sources 110 in an off state during the second time period Δt2. The first incident EM radiation has a first spectral band Δλ1 and the second incident EM radiation 126 has a second spectral band Δλ2. Responsive to the first incident EM radiation 124 and the second incident EM radiation 126, the image sensor 102 receives first reflected EM radiation 134 and second reflected EM radiation 136, which likewise have the first spectral band Δλ1 and the second spectral band Δλ2, respectively.

[0115] The image sensor 102 is configured to generate a second image signal 522 responsive to the first reflected EM radiation 134 and the second reflected EM radiation 136, which are, as discussed above, received responsive to the first incident EM radiation 124 and the second incident EM radiation 126 during the second time period Δt2. The image sensor 102 may measure, at each of the detector elements, an EM field and generate a corresponding electrical signal proportional to the measured EM field. Since EM radiation interferes linearly, the electric field at each of the detector elements is the sum of the electric field responsive to first incident EM radiation 124 alone and the electric field responsive to second incident EM radiation 126 alone. Accordingly, the sum represents a matrix of EM field values at the detector elements of the detectorsensor 102 during the second time period Δt2. Accordingly, the second image signal 522 may include a matrix of electrical signal values , which is proportional to the electric field values at the image23205EPP .

[0116] Since the incident second time period Δt2includes boththe first incident EM radiation 124 EM radiation 126, the spectral band of the electric field values at image sensor 102 includes both the first spectral band Δλ1 and the second sensor 102 provides the second imagesignal 522 ( ) to the stores the second image signal 522 to theone or more data storage devices 114 in image signals 120.

[0117] Since the second image signal 522 is proportional to the sum of electric field values for the first spectral band Δλ1 and the second spectral band Δλ2, the signal asecond processed image signal 524 ( ) by subtractingthe first image signal 518 ( ) (stored in the one or more data storage114 at imagesignals 120) from the second image signal 522 ( ):, which is proportional to, equivalently, proportional to :.The signal processing circuitry second processed image signal 524 () equal to the second image signal 522 ( ) minus the first image signal 518devices 114 in the processed signals 122.

[0118] With reference to FIG.5A and FIG.5B together, during a third image capture time period Δt3from a third time t3to another first time t1, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106, turns off and maintains off the one or more second illumination sources 108, and turns on and maintains turned on the one or more third illumination sources 110. As illustrated in FIG. 5B, the illumination control circuitry 130 maintains the first illumination control signal 508 and the third illumination control signal 512 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 and the one or more third23205EPP illumination sources 110 turned on during the Nth time period ΔtN. The illumination control circuitry 130 also switches the second illumination control signal 510 to and maintains the second illumination control signal 510 at a logic level low voltage potential to turn off and maintain turned off the one or more second illumination sources 108 during the third time period Δt3.

[0119] FIG. 5E illustrates the imaging system 100 of FIG. 1 during the third time period Δt3. As illustrated in FIG.5E, the illumination control circuitry 130 controls the one or more first illumination sources 106 and the one or more third illumination sources 110 to emit first incident EM radiation 124 and third incident EM radiation 128, respectively, toward the target 104 during the third time period Δt3. The illumination control circuitry 130 also controls the one or more second illumination sources 108 in an off state during the third time period Δt3. The first incident EM radiation has a first spectral band Δλ1 and the third incident EM radiation 128 has a third spectral band Δλ3. Responsive to the first incident EM radiation 124 and the third incident EM radiation 128, the image sensor 102 receives first reflected EM radiation 134 and third reflected EM radiation 138, which likewise have the first spectral band Δλ1 and the third spectral band Δλ3, respectively.

[0120] The image sensor 102 is configured to generate a third image signal 526 responsive to the first reflected EM radiation 134 and the third reflected EM radiation 138, which are, as discussed above, received responsive to the first incident EM radiation 124 and the third incident EM radiation 128 during the third time period Δt3. The image sensor 102 may measure, at each of the detector elements, an EM field and generate a corresponding electrical signal proportional to the measured EM field. Since EM radiation interferes linearly, the electric field at each of the detector elements is the sum of the electric field responsive to first incident EM radiation 124 alone with the electric field responsive to the third incident EM radiation 128 alone. Accordingly, the sum represents a matrix of EM field values at the detector elements of thethe image sensor 102 during the third time period Δt3. As a result, the third image signal 526 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor:.23205EPP

[0121] Since the incident EM radiation during the third time period Δt3includes the first incident EM radiation 124 and the third incident EM radiation 128, the spectral band of the electric field values at image sensor 102 includes the first spectral band Δλ1andthe third spectral sensor 102 provides the third image signal 526 ( ) tothe computing device 112, which stores the third image signal 526 to the one or datastorage devices 114 in image signals 120.

[0122] Since the third image signal 526 is proportional to the sum of electric field values for the first spectral band Δλ1 and the third spectral band Δλ3, thesignal generate a third processed image signal 528 ( ) bysubtracting the first image signals 518 ( ) (stored in the one or more data storage devices114 at image signals 120) from the third image signal 526 ( ):, which is proportional to, equivalently, proportional to :.

[0123] The signalto store the third processedimage signal 528 ( ) equal to the third image signal 526 ( ) minus the firstimage signal 218 ( ) to the one or more data storage devices 114 in processed signals 122.

[0124] To generalize the signal processing for the example illustrated in FIG. 5A through FIG.5E for an arbitrary number N of sets of one or more illumination sources, the following maybe used to obtain processed signals 122 ( , , … ):

[0125] Since thenot turn off sets of illumination sources between every one of the transitions between the time periods Δt1, Δt2, Δt3, (between first time period Δt1and second time period Δt2illumination sources are not turned off) these23205EPP time periods may be slightly shorter than in a scenario where the illumination control circuitry 130 was turning off sets of illumination sources between each time period. As a result, the example illustrated in FIG. 5A through FIG. 5E may cycle through time periods relatively faster compared to systems where sets of illumination sources are switched off between each time period. Accordingly, the example illustrated in FIG. 5A through FIG. 5E may enable a faster image acquisition rate.

[0126] Although the time periods are discussed in order from the first time period Δt1 to the third time period Δt3, the time periods may instead be cycled through in any other order. If the image signals are saved in image signals 120 of the one or more data storage devices 114, the signal processing circuitry 118 may generate the processed signals 122 from the image signals 120 regardless of the order in which the time periods are cycled through. Accordingly, in some embodiments, the illumination control circuitry 130 is configured to order the first time period, the second time period, and the third time period in sequence from the first time period to the second time period, and then to third time period. Also, in some embodiments, the illumination control circuitry 130 is configured to order the first time period, the second time period, and the third time period in a sequence different from starting from the first time period, transitioning to the second time period, and then transitioning to the third time period.

[0127] FIG. 6 is a flowchart illustrating a method 600 of operating an imaging system according to a one set of illumination sources always on pattern, according to some embodiments. At operation 602, method 600 includes operating one or more first illumination sources in an on state during a first time period. At operation 604, method 600 includes capturing a first image signal in the first time period. At operation 606, method 600 includes operating the one or more first illumination sources and one or more second illumination sources in the on state during a second time period. At operation 608, method 600 includes capturing a second image signal in the second time period. At operation 610, method 600 includes operating the one or more first illumination sources and one or more subsequent illumination sources in the on state during a subsequent time period. At operation 612, method 600 includes capturing a subsequent image signal in the subsequent time period. At operation 614, method 600 includes generating a first processed image signal to be the first image signal. At operation 616, method 600 includes generating a second processed image signal to be the23205EPP first image signal subtracted from the second image signal. At operation 618, method 600 includes generating a subsequent processed image signal to be the first image signal subtracted from the subsequent image signal.

[0128] FIG. 7 is a signal timing diagram of an example of illumination control signals 132 that may be used in a zig-zag illumination pattern in which one set of illumination sources is continuously on through the image capturing periods of time and the other sets of illumination sources are cycled through. The illumination control signals 132 in this example include a first illumination control signal 702, a second illumination control signal 704, and a third illumination control signal 706, which may be provided by the illumination control circuitry 130 of FIG. 1 to control the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG.1. In the first three time periods, Δt1, Δt2, and Δt3, the first illumination control signal 702, the second illumination control signal 704, and the third illumination control signal 706 may be controlled similarly to the first illumination control signal 508, the second illumination control signal 510, and the third illumination control signal 512 of FIG. 5B to capture a first image signal , a second image signal , and a third image signal in the first time periodtime periodΔt2, third time period Δt3,similar to the first image signal 518 ( ), thesecond image signal 522 ( ), and the third image signal 526 ( ) acquired as discussed abovewith reference toFIG. 5E.

[0129] Processed signals , , and corresponding to a first multispectral image 708 may be generated (e.g.,circuitry 118 of FIG. 1) responsive to first image signal , second image signal , and third image signal in a similar manner as discussed with reference to FIG.2AFIG.2E forprocessed signal , the second processed signal , and the third processed signal responsive tothe first image signal 518 ( ), the second image signal 522 ( ), and the third image signal526 ( ). The processed signals , , andbe stored in the processedsignals 122 of the one or more dataFIG. 1. For example, the processed signals , , and may be determined as:23205EPP .

[0130] At a fourth time control circuitry 130 (FIG. 1)maintains the first illumination control signal 702 and the second illumination control signal 704 at logic level high voltage potentials that are sufficiently high to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 (FIG. 1) in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 706 at a logic level low voltage potential to operate the one or more third illumination sources 110 in an off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the imagethe one or more data storage devices 114 of FIG. 1).

[0131] At a fifth time period Δt5, the illumination control circuitry 130 (FIG.1) maintains the first illumination control signal 702 at a logic level high voltage potential to operate the one or more first illumination sources 106 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 704 and the third illumination control signal 706 at logic level low voltage potentials to operate the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 or more data storage devices 114 of FIG. 1).

[0132] Processed signals , , and corresponding to a second multispectral image 710 may beprocessing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more data storage devices 114 of example, processed signals , , and may be determined to be:23205EPP .

[0133] At a sixth time circuitry 130 (FIG.1) maintainsthe first illumination control signal 702 and the second illumination control signal 704 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 706 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 one or more data storage devices 114 of FIG. 1).

[0134] At a seventh time period Δt7, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 702 and the third illumination control signal 706 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more third illumination sources 110 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 704 at a logic level low voltage potential to operate the one or more second illumination sources 108 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG. 1).

[0135] Processed signals , , and corresponding to a third multispectral image 712 may be generated (e.g.,circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored in processedone or more dataFor example, processed signals , , and may be determined to be: .23205EPP

[0136] At an eighth time period Δt8, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 702 and the second illumination control signal 704 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 706 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signalsone or more data storage devices 114 of FIG.1).

[0137] At a ninth time period Δt9, the illumination control circuitry 130 (FIG.1) maintains the first illumination control signal 702 at a logic level high voltage potential to operate the one or more first illumination sources 106 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 704 and the third illumination control signal 706 at logic level low voltage potentials to operate the one or more second illumination sources 108 and the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG. 1).

[0138] Processed signals , , and corresponding to a fourth multispectral image 714 may beprocessing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more data114 of example, processed signals , , and may be determined to be:.

[0139] At a tenth time period Δt10, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 702 and the second illumination control signal 704 at logic level high voltage potentials to operate the one or more first illumination sources 10623205EPP and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 706 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals one or more data storage devices 114 of FIG.1).

[0140] At an eleventh time period Δt11, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 702 and the third illumination control signal 706 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more third illumination sources 110 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 704 at a logic level low voltage potential to operate the one or more second illumination sources 108 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals 120one or more data storage devices 114 of FIG. 1).

[0141] Processed signals , , and corresponding to a fifth multispectral image 716 may be generatedthe signal processing circuitry 118 of FIG. 1) responsive to image signals , , and . The processed signals , , and may be stored inone or more dataFor example, processed signals , , and may be determined to be:.

[0142] At a twelfth timecontrol circuitry 130 (FIG. 1) maintains the first illumination control signal 702 and the second illumination control signal 704 at logic level high voltage potentials to operate the one or more first illumination sources 106 and the one or more second illumination sources 108 in a turned on state. The illumination control circuitry 130 also maintains the third illumination control signal 706 at a logic level low voltage potential to operate the one or more third illumination sources 110 in a turned off state.23205EPP An image signal is captured (e.g., by the image sensor 102 of FIG. 1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG.1).

[0143] At a thirteenth time period Δt13, the illumination control circuitry 130 (FIG. 1) maintains the first illumination control signal 702 at a logic level high voltage potential to operate the one or more first illumination sources 106 in a turned on state. The illumination control circuitry 130 also maintains the second illumination control signal 704 and the third illumination control signal 706 at logic level low voltage potentials to operate the one or more second illumination sources 108 and the one or more third illumination sources 110 in a turned off state. An image signal is captured (e.g., by the image sensor 102 of FIG.1) and stored (in the image signals 120 of the one or more data storage devices 114 of FIG. 1).

[0144] Processed signals , , and corresponding to a sixth multispectral image 718 may be generated processing circuitry 118 of FIG. 1) responsiveto image signals , , and . The processed signals , , and may be stored inone or more dataFor example, processed signals , , and may be determined to be:.

[0145] In this example, sixincluding three processed signals corresponding to three different spectral bands, were generated over thirteen time periods. By comparison, the example illustrated in FIG.5A through FIG.5E would take eighteen time periods to generate six multispectral images including three processed signals each. Accordingly, the zig-zag illumination pattern illustrated in FIG. 7 results in a faster effective acquisition rate for multispectral images as compared to the illumination pattern of FIG.5A through FIG.5E. Where three sets of one or more illumination sources are used, the zig-zag illumination pattern of FIG. 7 results in about a 33% faster effective acquisition rate for multispectral images than the illumination example of FIG. 5A through FIG. 5E. Where four sets of one or more illumination23205EPP sources are used, the zig-zag illumination pattern of FIG.7 result in about a 25% faster effective acquisition rate of multispectral images than the illumination example of FIG. 5A through FIG. 5E. Where five sets of one or more illumination sources are used, the zig-zag illumination pattern of FIG. 7 result in about a 20% faster effective acquisition rate of multispectral images than the illumination example of FIG. 5A through FIG. 5E.

[0146] FIG. 8A through FIG. 8E illustrate an example of operation of the imaging system 100 of FIG.1 in which two sets of illumination sources are switched on at a time. In this example, a first image signal may be captured (e.g., using the image sensor 102 of FIG. 1) while two sets of illumination sources are on. In each successive time period in a cycle, a different two sets of illumination sources are on and corresponding image signals are captured. Signal processing may be performed on the image signals to separate the individual spectral bands (e.g., Δλ1, Δλ2, and Δλ3 of FIG.1) corresponding to the sets of illumination sources, as will be discussed in more detail below.

[0147] FIG. 8A is a portion of the imaging system 100 of FIG. 1 to illustrate illumination control signals 132 that may be used in this example of two on at a time operation. FIG. 8A illustrates the illumination control circuitry 130, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG.1. FIG.8A also illustrates the illumination control signals 132 of FIG.1, which in this example include a first illumination control signal 808 (shown using an arrow with a solid line), a second illumination control signal 810 (shown using an arrow with a dashed line), and a third illumination control signal 812 (shown using an arrow with a dotted line).

[0148] The illumination control circuitry 130 is configured to selectively and separately control each of the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 using the first illumination control signal 808, the second illumination control signal 810, and the third illumination control signal 812, respectively.

[0149] FIG. 8B is a signal timing diagram illustrating the illumination control signals 132 of FIG. 8A plotted against time. The signal timing diagram includes separate plots for first illumination control signal 808, which is used for controlling the one or more first illumination sources 106 of FIG. 8A, second illumination control signal 810, which is used for controlling the23205EPP one or more second illumination sources 108 of FIG. 8A, and third illumination control signal 812, which is used for controlling the one or more third illumination sources 110 of FIG.8A. The vertical axes for these plots are volts and the horizontal axes for these plots are units of time.

[0150] The plots in FIG. 8B include two cycles of three time periods Δt1, Δt2, and Δt3. Where the number of sets of illumination sources is greater than three, however, the number of time periods in each cycle would be greater than three, and only three time periods are illustrated in FIG.8B in each cycle for ease of the disclosure.

[0151] Referring to FIG. 8A and FIG. 8B together, during a first time period Δt1 from a first time t1 to a second time t2, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more second illumination sources 108, and maintains turned off the one or more third illumination sources 110. As illustrated in FIG.8B, the illumination control circuitry 130 maintains the first illumination control signal 808 and the second illumination control signal 810 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 and the one or more second illumination sources 108 on during the first time period Δt1. As also illustrated in FIG. 8B, the illumination control circuitry 130 maintains the third illumination control signal 812 at a logic level low voltage potential to maintain the one or more third illumination sources 110 in an off state.

[0152] FIG. 8C illustrates the imaging system 100 of FIG. 1 during the first time period Δt1. As illustrated in FIG.8C, the illumination control circuitry 130 controls the one or more first illumination sources 106 and the one or more second illumination sources 108 to emit first incident EM radiation 124 and second incident EM radiation 126, respectively, toward the target 104 and maintains the one or more third illumination sources 110 in an off state during the first time period Δt1. The first incident EM radiation 124 has a first spectral band Δλ1and the second incident EM radiation 126 has a second spectral band Δλ2. Responsive to the first incident EM radiation 124 and the second incident EM radiation 126, the image sensor 102 receives first reflected EM radiation 134 and second reflected EM radiation 136, which have the first spectral band Δλ1and the second spectral band Δλ2, respectively.

[0153] The image sensor 102 is configured to generate a first image signal 818 responsive to the first reflected EM radiation 134 and the second reflected EM radiation 136, which are, as23205EPP discussed above, received responsive to the first incident EM radiation 124 and the second incident EM radiation 126 during the first time period Δt1. At each of the detector elements of the image sensor 102, the image sensor 102 may measure an EM field and generate a corresponding electrical signal proportional to the measured EM field. represents a matrix of EM field values at the detector elements of the detector sensor 102 during the first time period Δt1. Accordingly, the first image signal818 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor:.

[0154] Since the incident EM first time period Δt1includes the first incident EM radiation 124 and the second incident EM radiation 126, the spectral band of the electric field values at image sensor 102 includes the first spectral band Δλ1 and the secondfirst image signal 818, therefore corresponds to the first spectral band Δλ1and the second spectral band Δλ2. The image sensor 102 provides the firstimage signal 818 ( ) to the computing device 112, which stores the first image signal 818 tothe one or more data storage devices 114 (e.g., in image signals 120).

[0155] Since the first image signal 818 is proportional to the electric field values for the first spectral band Δλ1and the second spectral band Δλ2, the signalseparate the different spectral bands using signal processing after acquiring further image signals.

[0156] With reference to FIG. 8A and FIG. 8B together, during a second image capture time period Δt2(also referred to herein simply as “second time period Δt2”) from a second time t2to a third time t3, the illumination control circuitry 130 maintains turned on the one or more second illumination sources 108, turns on and maintains turned on the one or more third illumination sources 110, and turns off and maintains turned off the one or more first illumination sources 106. As illustrated in FIG. 8B, the illumination control circuitry 130 maintains the second illumination control signal 810 and the third illumination control signal 812 at logic level high voltage potentials corresponding to sufficiently high voltage potentials23205EPP to maintain the one or more second illumination sources 108 and the one or more third illumination sources 110 on during the second time period Δt2. As also illustrated in FIG. 8B, the illumination control circuitry 130 maintains the first illumination control signal 808 at a logic level low voltage potential to maintain the one or more first illumination sources 106 in an off state.

[0157] FIG.8D illustrates the imaging system 100 of FIG.1 during the second time period Δt2. As illustrated in FIG. 8D, the illumination control circuitry 130 controls the one or more second illumination sources 108 and the one or more third illumination sources 110 to emit second incident EM radiation 126 and third incident EM radiation 128, respectively, toward the target 104 and maintains the one or more first illumination sources 106 in an off state during the second time period Δt2. The second incident EM radiation 126 has a second spectral band Δλ2 and the third incident EM radiation 128 has a third spectral band Δλ3. Responsive to the second incident EM radiation 126 and the third incident EM radiation 128, the image sensor 102 receives second reflected EM radiation 136 and third reflected EM radiation 138, which likewise have the second spectral band Δλ2 and the third spectral band Δλ3, respectively.

[0158] The image sensor 102 is configured to generate a second image signal 822 responsive to the second reflected EM radiation 136 and the third reflected EM radiation 138, which are, as discussed above, received responsive to the second incident EM radiation 126 and the third incident EM radiation 128 during the second time period Δt2. The image sensor 102 may measure, at each of the detector elements, an EM field and generate a corresponding electrical signal proportional to the measured EM field. Since EM radiation interferes linearly, the electric field at each of the detector elements is the sum of the electric field responsive to second incident EM radiation 126 alone and the electric field responsive to third incident EM radiation 128 alone. Accordingly, the sum represents a matrix of EM field values at the detector elements of the detectorsensor 102 during the second time period Δt2. Accordingly, the second image signal 822 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor:.23205EPP

[0159] Since the incident EM radiation during the second time period Δt2includes both the second incident EM radiation 126 and the third incident EM radiation 128, the spectral band of the electric field values at image sensor 102 includes both the first spectral band Δλ1and the second Δλ2. The image sensor 102 provides the second imagesignal 822 ( ) to the computing device 112, which stores the second image signal 822 to theone or more data storage devices 114 in image signals 120.

[0160] Since the second image signal 822 is proportional to the sum of electric field values for the second spectral band Δλ2 and the third spectral band Δλ3, the signal 118 may separate the different spectral bands using signal processingafter acquiring further image signals.

[0161] With reference to FIG.8A and FIG.8B together, during a third image capture time period Δt3 from a third time t3 to another first time t1, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106, turns off and maintains off the one or more second illumination sources 108, and turns on and maintains on the one or more third illumination sources 110. As illustrated in FIG. 8B, the illumination control circuitry 130 maintains the first illumination control signal 808 and the third illumination control signal 812 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 and the one or more third illumination sources 110 on during the third time period Δt3. The illumination control circuitry 130 also switches the second illumination control signal 810 to and maintains the second illumination control signal 810 at a logic level low voltage potential to turn and maintain the one or more second illumination sources 108 in an off state during the third time period Δt3.

[0162] FIG. 8E illustrates the imaging system 100 of FIG. 1 during the third time period ΔtN. As illustrated in FIG.8E, the illumination control circuitry 130 controls the one or more first illumination sources 106 and the one or more third illumination sources 110 to emit first incident EM radiation 124 and third incident EM radiation 128, respectively, toward the target 104 during the third time period Δt3. The illumination control circuitry 130 also maintains the one or more second illumination sources 108 in an off state during the third time period Δt3. The first incident EM radiation has a first spectral band Δλ1and the third incident EM radiation 128 has a third spectral band Δλ3. Responsive to the first incident EM radiation 124 and the23205EPP third incident EM radiation 128, the image sensor 102 receives first reflected EM radiation 134 and third reflected EM radiation 138, which likewise have the first spectral band Δλ1and the third spectral band Δλ3, respectively.

[0163] The image sensor 102 is configured to generate a third image signal 826 responsive to the first reflected EM radiation 134 and the third reflected EM radiation 138, which are, as discussed above, received responsive to the first incident EM radiation 124 and the third incident EM radiation 128 during the third time period Δt3. The image sensor 102 may measure, at each of the detector elements, an EM field and generate a corresponding electrical signal proportional to the measured EM field. Since EM radiation interferes linearly, the electric field at each of the detector elements is the sum of the electric field responsive to first incident EM radiation 124 alone with the electric field responsive to the third incident EM radiation 128 alone. Accordingly, the sum represents a matrix of EM field values at the detector elements of the detector array of the image sensor 102 during the third time period Δt3. As a result, the third image signal 826 may include a matrix of electrical signal values , which is proportional to the electric field values at the image sensor: .

[0164] Since the incident EM radiation during the third time period Δt3 includes the first incident EM radiation 124 and the third incident EM radiation 128, the spectral band of the electric field values at image sensor 102 includes the first spectral band Δλ1 andthe third spectralThe image sensor 102 provides the third image signal 826 ( ) tothe computing device 114, which stores the third image signal 826 to the one ordata storage devices 114 in image signals 120.

[0165] The image signals 120 accrued through time period Δt3include the following: first image signal 818: ,second image signal 822: , andthird image signal 826: .23205EPP The signal processing circuitry 118 is configured to generate processed signals 122 responsive to the image signals 120. The processed signals 122 may include a first processed image signal820 ( ) corresponding to the first spectral band Δλ1, a second processed image signal 824 () corresponding to the second spectral band Δλ2, and a third processed image signal 828 ( ) corresponding to the third spectral band Δλ3.

[0166] The signal processing circuitry 118 is configured to use the first image signal 818( ), the second image signal 822 ( ), and the third imagespecifically, the signal processing circuitry 118 is configured to generate the first processed image signal 820 such that the first processed image signal 820 is proportional to the first spectral band Δλ1component of the image signals 120. By way of non-limiting example,the signal processing circuitry 118 may generate the first processed image signal 820 ( ) tobe: .Since , , , it follows that:,and finally .23205EPP

[0167] In some embodiments, for the sake of simplicity, the first processed image signal 820 may instead be set to be: , which mathematically results in:, as will be apparent from the abovefactor of two in this case may be cancelled out through calibration (e.g., resulting in lower power being expended by the illumination sources), or kept for an effectively higher brightness first processed image signal 820.

[0168] The signal processing circuitry 118 is also configured to use the first image signal818 ( ), the second image signal 822 ( ), and the third) to generate thesignal 824 (). Morecircuitry 118 is configured to generate the second processed image signal 824 such that the second processed image signal 824 is proportional to the second spectral band Δλ2 component of the image signals 120. By way of non-limiting example, the signal processing circuitry 118 may generate the second processed image signal824 ( ) to be:.23205EPP and finally .

[0169] In some embodiments, for the sake of simplicity, the first processed image signal 820 may instead be set to be: , which mathematically results in:, as will be apparent from the above mathematics. The factor of two in this case may be cancelled out through calibration (e.g., resulting in lower power being expended by the illumination sources), or kept for an effectively higher brightness second processed image signal 824.

[0170] The signal processing circuitry 118 is further configured to use the first imagesignal 818 ( ), the second image signal 822 ( ), and thethird) to generate thesignal 828 (). Morecircuitry 118 is configured to generate the third processed image signal 828 such that the third processed image signal 828 is proportional to the third spectral band Δλ3component of the image signals 120. By way of non-limiting example, the signal processing circuitry 118 may generate the third processed image signal 828( ) to be:23205EPP , and finally.

[0171] In some embodiments, simplicity, the first processed image signal820 may instead be set to be: , which mathematically results in:, as will be apparent from the abovefactor of two in this case may be cancelled out through calibration (e.g., resulting in lower power being expended by the illumination sources), or kept for an effectively higher brightness third processed image signal 828.

[0172] The signal processing circuitry 118 is configured to provide the first processed image signal 820, the second processed image signal 824, and the third processed image signal 828 (e.g., determined as outlined above) to the one or more data storage devices 114 to store in the processed signals 122. A multispectral image based on the processed signals 122 may in this way be generated.

[0173] FIG. 9A illustrates an example of an implementation of a portion of the imaging system 100 of FIG. 1 similar to the stepped example of FIG. 2A through FIG. 2E using four sets of illumination sources. In this example, the sets of illumination sources include the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG.1. The illumination sources also include one or more fourth illumination sources 930 configured to selectively provide incident illumination having a fourth spectral band Δλ4.23205EPP

[0174] In this example, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 may include infrared illumination sources of different spectral bands Δλ1, Δλ2, and Δλ3. By way of non-limiting example, the spectral bands Δλ1, Δλ2, and Δλ3may be taken from a 730 nm to a 1900 nm range. Also by way of non-limiting example, the spectral bands Δλ1, Δλ2, and Δλ3 may be taken from a 400 nm to 2,000 nm range. As a specific, non-limiting example, the first spectral band Δλ1 may be centered at substantially 850 nm.

[0175] By way of non-limiting example, the one or more fourth illumination sources 930 may be a RGB broad spectrum illumination sources that emit EM radiation in a visible spectral band (e.g., at least substantially between 380 nm and 750 nm). The one or more fourth illumination sources 930 may be maintained on similar to the one or more first illumination sources 106 in the example of FIG. 2A through FIG. 2E.

[0176] An image signal may be captured (e.g., using the image sensor 102 of FIG. 1) as each set of illumination sources is turned on, and signal processing may be performed on the image signals to separate the individual spectral bands (e.g., Δλ1, Δλ2, and Δλ3) corresponding to the sets of illumination sources from the image signals 120. Specifically, the first image signal may be taken as the first processed image signal, and each subsequent processed image signal may be the current image signal minus the previous image signal. As a result, a multispectral image including sub-images corresponding to the individual spectral bands may be obtained. Since the one or more fourth illumination sources 930 remains on through the cycling of illumination and image capturing, the image signals may include components of the fourth spectral band Δλ4 in each image signal. Signal processing, however, may be performed similarly as for the example of FIG.2A through FIG. 2E, and the first processed signal may therefore also include components of the fourth spectral band Δλ4but the fourth spectral band may be removed from the second and third processed signals.

[0177] The illumination control circuitry 130 is configured to selectively and separately control each of the one or more first illumination sources 106, the one or more second illumination sources 108, the one or more third illumination sources 110, and the one or more fourth illumination sources 930 using the first illumination control signal 908, the second23205EPP illumination control signal 910, the third illumination control signal 912, and the fourth illumination control signal 932, respectively.

[0178] FIG. 9B is a signal timing diagram illustrating the illumination control signals 132 of FIG. 9A plotted against time. The signal timing diagram includes separate plots for first illumination control signal 908 (used for controlling the one or more first illumination sources 106 of FIG. 9A), second illumination control signal 910 (used for controlling the one or more second illumination sources 108 of FIG. 9A), third illumination control signal 912 (used for controlling the one or more third illumination sources 110 of FIG. 9A), and fourth illumination control signal 932 (used for controlling the one or more fourth illumination sources 930 of FIG. 9A). The vertical axes for these plots are volts and the horizontal axes for these plots are units of time.

[0179] The plots for the first illumination control signal 908, the second illumination control signal 910, and the third illumination control signal 912 in FIG. 9B are similar to those discussed above for FIG. 2B. The plot for fourth illumination control signal 932 is similar to that for first illumination control signal 908. Accordingly, when the one or more first illumination sources 106 are on in this example, the one or more fourth illumination sources 930 are also on.

[0180] Referring to FIG.9A and FIG.9B together, during a first image capture time period Δt1 (also referred to herein simply as “first time period Δt1”) from a first time t1 to a second time t2, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more fourth illumination sources 930 and maintains turned off the one or more second illumination sources 108 and the one or more third illumination sources 110. As illustrated in FIG. 9B, the illumination control circuitry 130 maintains the first illumination control signal 908 and the fourth illumination control signal 932 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 on during the first time period Δt1. As also illustrated in FIG. 9B, the illumination control circuitry 130 maintains the second illumination control signal 910 and the third illumination control signal 912 at a logic level low voltage potential to maintain the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state.23205EPP

[0181] From the second time t2to a third time t3(the second time period Δt2), the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more fourth illumination sources 930 and turns on and maintains on the one or more second illumination sources 108. The illumination control circuitry 130 maintains off the one or more third illumination sources 110.

[0182] From the third time t3 to another first time t1 (the third time period Δt3), the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more fourth illumination sources 930. The illumination control circuitry 130 also turns on and maintains on the one or more third illumination sources 110.

[0183] FIG. 10A illustrates an example of an implementation of a portion of the imaging system 100 of FIG. 1 similar to the one set of illumination sources continuously on example of FIG. 5A through FIG. 5E using four sets of illumination sources. In this example, the sets of illumination sources include the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG. 1. The illumination sources also include one or more fourth illumination sources 1030 configured to selectively provide incident illumination having a fourth spectral band Δλ4.

[0184] In this example, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 may include infrared illumination sources of different spectral bands Δλ1, Δλ2, and Δλ3. By way of non-limiting example, the spectral bands Δλ1, Δλ2, and Δλ3 may be taken from a 730 nm to a 1900 nm range. Also by way of non-limiting example, the spectral bands Δλ1, Δλ2, and Δλ3 may be taken from a 400 nm to 2,000 nm range. As a specific, non-limiting example, the first spectral band Δλ1may be centered at substantially 850 nm.

[0185] By way of non-limiting example, the one or more fourth illumination sources 1030 may be one or more RGB broad spectrum illumination sources that emit EM radiation in a visible spectral band (e.g., at least substantially between 380 nm and 750 nm). The one or more fourth illumination sources 1030 may be maintained on similar to the one or more first illumination sources 106 in the example of FIG. 2A through FIG. 2E.23205EPP

[0186] An image signal may be captured (e.g., using the image sensor 102 of FIG. 1) as each set of illumination sources is turned on, and signal processing may be performed on the image signals to separate the individual spectral bands (e.g., Δλ1, Δλ2, and Δλ3) corresponding to the sets of illumination sources from the image signals 120. Specifically, the first image signal may be taken as the first processed image signal, and each subsequent processed image signal may be the current image signal minus the first image signal. As a result, a multispectral image including sub-images corresponding to the individual spectral bands may be obtained. Since the one or more fourth illumination sources 1030 remains on through the cycling of illumination and image capturing, the image signals may include components of the fourth spectral band Δλ4 in each image signal. Signal processing, however, may be performed similarly as for the example of FIG.5A through FIG.5E, and the first processed signal may therefore also include components of the fourth spectral band Δλ4 but the fourth spectral band may be removed from the second and third processed signals.

[0187] The illumination control circuitry 130 is configured to selectively and separately control each of the one or more first illumination sources 106, the one or more second illumination sources 108, the one or more third illumination sources 110, and the one or more fourth illumination sources 1030 using the first illumination control signal 1008, the second illumination control signal 1010, the third illumination control signal 1012, and the fourth illumination control signal 1032, respectively.

[0188] FIG.10B is a signal timing diagram illustrating the illumination control signals 132 of FIG. 10A plotted against time. The signal timing diagram includes separate plots for first illumination control signal 1008 (used for controlling the one or more first illumination sources 106 of FIG. 10A), second illumination control signal 1010 (used for controlling the one or more second illumination sources 108 of FIG. 10A), third illumination control signal 1012 (used for controlling the one or more third illumination sources 110 of FIG. 10A), and fourth illumination control signal 1032 (used for controlling the one or more fourth illumination sources 1030 of FIG. 10A). The vertical axes for these plots are volts and the horizontal axes for these plots are units of time.

[0189] The plots for the first illumination control signal 1008, the second illumination control signal 1010, and the third illumination control signal 1012 in FIG.10B are similar to those23205EPP discussed above for FIG.5B. The plot for fourth illumination control signal 1032 is similar to that for first illumination control signal 1008. Accordingly, when the one or more first illumination sources 106 are on in this example, the one or more fourth illumination sources 1030 are also on.

[0190] Referring to FIG. 10A and FIG. 10B together, during a first time period Δt1 from a first time t1 to a second time t2, the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more fourth illumination sources 1030 and maintains turned off the one or more second illumination sources 108 and the one or more third illumination sources 110. As illustrated in FIG. 10B, the illumination control circuitry 130 maintains the first illumination control signal 1008 and the fourth illumination control signal 1032 at logic level high voltage potentials corresponding to sufficiently high voltage potentials to maintain the one or more first illumination sources 106 on during the first time period Δt1. As also illustrated in FIG. 10B, the illumination control circuitry 130 maintains the second illumination control signal 1010 and the third illumination control signal 1012 at a logic level low voltage potential to maintain the one or more second illumination sources 108 and the one or more third illumination sources 110 in an off state.

[0191] From the second time t2 to a third time t3 (the second time period Δt2), the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more fourth illumination sources 1030 and turns on and maintains on the one or more second illumination sources 108. The illumination control circuitry 130 maintains off the one or more third illumination sources 110.

[0192] From the third time t3 to another first time t1 (the third time period Δt3), the illumination control circuitry 130 maintains turned on the one or more first illumination sources 106 and the one or more fourth illumination sources 1030. The illumination control circuitry 130 also turns on and maintains turned on the one or more third illumination sources 110. The illumination control circuitry 130 further turns off and maintains off the one or more second illumination sources 108.

[0193] In this example, a first camera (e.g., the image sensor 102 of FIG.1) comprising a shortwave infrared (SWIR) camera may be used to acquire images having the second spectral band Δλ2and the third spectral band Δλ3and a broad band line scanning camera (e.g., the Linea223205EPP camera by Teledyne Technologies of Thousand Oaks, California) may be used to capture the first spectral band Δλ1.

[0194] FIG. 11 is a schematic representation of a sorter device 1102 according to some embodiments. The sorter device 1102 may include a support frame 1104 supporting an infeed system 1106, at least one detection system 1108, at least one ejector 1110, and a plurality of collection bins 1112. Furthermore, the sorter device 1102 may include a system controller 1114 (e.g., the computing device 112 of FIG. 1) to which the infeed system 1106, the at least one detection system 1108, and the at least one ejector 1110 are operably coupled. As is described in greater detail below, the sorter device 1102 may be utilized to sort bulk product (e.g., granular product) such as, for example, nuts, seeds, grain, plastic pieces, etc. The sorter device 1102 may sort the pieces of the bulk product 1116 (referred to hereinafter as “grains”) based on one or more of the grains' sizes, shapes, colors, types, chemical characteristics, or materials. In particular, the sorter device 1102 may sort the grains of the bulk product 1116 according to preselected sorting criteria. As a non-limiting example, the sorter device 1102 may be utilized to sort grain based on quality of the grain, which, in some instances, may be determined by a color of the grain. As another non-limiting example, the sorter device 1102 may be utilized to sort bulk plastic pieces based on plastic type.

[0195] The infeed system 1106 of the sorter device 1102 may include a hopper 1118 and a chute and / or belt 1120. The hopper 1118 may define a pathway for the bulk product 1116 to the chute and / or belt 1120, and in some embodiments, the hopper 1118 may include one or more vibrators (e.g., a vibrator feeder), augers, or other feeders to feed the bulk product 1116 from the hopper 1118 to the chute and / or belt 1120. The chute and / or belt 1120 may be sized, shaped, and oriented to cause the bulk product 1116 to descend due to gravity and / or a conveyor belt in order to pass in front of the at least one detection system 1108. For instance, the chute and / or belt 1120 may be configured to produce a stream 1122 of the bulk product 1116 to pass in front of the at least one detection system 1108 according to a selected velocity (e.g., speed).

[0196] The at least one detection system 1108 may include a plurality of illumination sources 1124, one or more background elements 1126, one or more image sensors 1128, a plurality of intensity sensors 1130, a plurality of current sensors 1132, and a plurality of23205EPP reference elements 1134. The plurality of illumination sources 1124 may be configured to emit electromagnetic radiation at the stream 1122 of the bulk product 1116 as it passes in front of the at least one detection system 1108. For example, the plurality of illumination sources 1124 may include one or more light-emitting-diodes (LEDs) for emitting light. In some embodiments, the plurality of illumination sources 1124 may emit one or more of visible light, short-wave infrared light (SWIR light), near infrared light (NIR light), infrared (IR) light, or ultra-violet (UV) light. In one or more embodiments, the plurality of emitting devices plurality of illumination sources 1124 may be configured to emit light within a specific (e.g., selected) spectral band of the electromagnetic spectrum. In some embodiments, the plurality of illumination sources 1124 may include at least four illumination sources. In one or more embodiments, at least one of the at least four illumination sources may be configured to emit a first type of electromagnetic radiation (e.g., UV light), and at least one of the at least four illumination sources may be configured to emit a second type of electromagnetic radiation (e.g., NIR light). In some embodiments, a given illumination source of the plurality of illumination sources 1124 may be implemented as a standalone illumination source of a specific spectral band. In some embodiments multiple illumination sources may be implemented into a single package (e.g., two or more LEDs having different spectral bands may be implemented into a single package).

[0197] In some embodiments, the plurality of illumination sources 1124 may include the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 of FIG. 1. In some embodiments the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 include infrared (e.g., NIR) illumination sources (e.g., NIR LEDs) of different infrared spectral bands. By way of non-limiting example, the plurality of illumination sources 1124 may include one or more visible illumination sources in addition to the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110. For example, the plurality of illumination sources 1124 may include one or more red-green-blue (RGB) illumination sources configured to emit broad spectrum EM radiation that covers the visible spectral band (e.g., at least substantially between 380 nm and 750 nm). In some embodiments the one or more visible illumination sources may be maintained on while the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination23205EPP sources 110, operating at different infrared spectral bands, are operated according to the illumination sequences discussed above with reference to FIG. 2A through FIG. 2E, FIG. 5A through FIG.5E, FIG.4, FIG.7, FIG. 8A through FIG.8E, FIG.9A and FIG. 9B, or FIG.10A and FIG. 10B.

[0198] In a specific, non-limiting example of operation of the sorter device 1102 according to FIG. 9A and FIG. 9B, the one or more first illumination sources 106 may be kept constantly on along with one or more visible illumination sources while the one or more second illumination sources 108 and the one or more third illumination sources 110 are pulsed in different time periods as discussed with reference to FIG. 9A and FIG. 9B. In this example, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 may include infrared illumination sources of different spectral bands. By way of non-limiting example, a spectral band of the one or more first illumination sources 106 may be centered at substantially 850 nm.

[0199] In a specific, non-limiting example of operation of the sorter device 1102 according to FIG. 10A and FIG. 10B, the one or more first illumination sources 106 may be kept constantly on along with one or more visible illumination sources while the one or more second illumination sources 108 and the one or more third illumination sources 110 are pulsed in different time periods as discussed with reference to FIG. 10A and FIG. 10B. In this example, the one or more first illumination sources 106, the one or more second illumination sources 108, and the one or more third illumination sources 110 may include infrared illumination sources of different spectral bands. By way of non-limiting example, a spectral band of the one or more first illumination sources 106 may be centered at substantially 850 nm.

[0200] The one or more image sensors 1128 may include one or more of a charged- coupled device (CCD) camera, an IR camera, a UV camera, or an RGB camera. During use, the one or more image sensors 1128 may be oriented and configure to detect (e.g., capture) light reflected from the stream 1122 of the bulk product 1116 due to the plurality of illumination sources 1124. For instance, the fields of views of the one or more image sensors 1128 may include at least a portion of the stream 1122 of bulk product 1116. In one or more embodiments, the at least one detection system 1108 may further include one or more optical filters for filtering (e.g., narrowing) the reflected light being detected (e.g., captured) by the23205EPP one or more image sensors 1128. In some embodiments, the one or more optical filters may narrow the reflected light into specific (e.g., selected) wavelengths that may accentuate sorting criteria (e.g., criteria distinguishing grades or types of bulk products).

[0201] As a non-limiting example of a monochromatic sorter device, the at least one detection system 1108 may include a single optical filter between the stream 1122 of the bulk product 1116 and a respective one of the one or more image sensors 1128. The single optical filter may produce, for example, a light / dark separation. As another non-limiting example of a bi-chromatic sorter device, the at least one detection system 1108 may include two optical filters between the stream 1122 of bulk product 1116 and a respective one of the one or more image sensors 1128. For example, the at least one detection system 1108 may include any two conventional optical filters.

[0202] As noted above, the at least one detection system 1108 may include one or more background elements 1126, and the one or more background elements 1126 may be disposed and oriented behind the stream 1122 relative to the one or more image sensors 1128. The one or more background elements 1126 provide better detection and imaging of the individual grains of the bulk product 1116. For example, the one or more background elements 1126 may include any known background elements.

[0203] The plurality of intensity sensors 1130 may be oriented relative to the plurality of illumination sources 1124 such that the plurality of intensity sensors 1130 may be utilized to measure an intensity of the light being emitted by the plurality of illumination sources 1124. For instance, in some embodiments, the plurality of intensity sensors 1130 may be disposed between the plurality of illumination sources 1124 and the stream 1122 of bulk product 1116. In additional embodiments, the plurality of intensity sensors 1130 may be disposed anywhere within the sorter device 1102 such that the plurality of intensity sensors 1130 is exposed to the light emitted by the plurality of illumination sources 1124. In some embodiments, each of the plurality of intensity sensors 1130 may be associated with a respective one of the plurality of illumination sources 1124. In one or more embodiments, the plurality of intensity sensors 1130 may include one or more photodiodes, photoresistors, phototransistors, or photovoltaic light sensors.23205EPP

[0204] Furthermore, each of the plurality of intensity sensors 1130 may be configured to measure an at least substantially instantaneous intensity of light experienced by the intensity sensor 1130. In some embodiments, the plurality of intensity sensors 1130 may be configured to measure at least two intensity values of the light experienced by the intensity sensor 1130. For example, the plurality of intensity sensors 1130 may be configured to measure at least SWIR intensity and visible light intensity. While SWIR light and visible light are listed as examples, the disclosure is not so limited. Rather, the plurality of intensity sensors 1130 may be configured to measure an intensity of one or more of IR light, NIR light, SWIR light, UV light, or visible light.

[0205] Referring still to FIG. 11, the plurality of current sensors 1132 may be operably coupled to the plurality of illumination sources 1124. For instance, each of the plurality of current sensors 1132 may be operably coupled to a respective one of the plurality of illumination sources 1124. Each of the plurality of current sensors 1132 may be configured to measure a current being supplied to a respective illumination source 1124. For example, each of the plurality of current sensors 1132 may be configured to measure a current being supplied to a respective one of the plurality of illumination sources 1124 over a specified period of time. In some embodiments, the specified period of time may be 500 nanoseconds (ns), 1.0 microsecond (μs), 5.0 microseconds (μs), or 10.0 microseconds (μs). Furthermore, as is described in greater detail below, the current being supplied to one of the plurality of illumination sources 1124 over the specified period of time can be correlated to an emitted light intensity. In some embodiments, current values can be measured for one or more of IR light, NIR light, SWIR light, UV light, or visible light. In one or more embodiments, the measured current values may be correlated to light intensities measured via the plurality of intensity sensors 1130. For instance, the current being supplied to a respective illumination source 1124 can be measured at a same time that the instantaneous intensity of light is being measured by an intensity sensor 1130.

[0206] As noted above, the at least one detection system 1108 may include a plurality of reference elements 1134. Each reference element of the plurality of reference elements 1134 may be disposed within a field of view of the one or more image sensors 1128. In some embodiments, each reference element 1134 may have an at least substantially constant color and / or may exhibit an at least substantially constant color. As a non-limiting example, each of23205EPP the plurality of reference elements 1134 may include a colored piston within a clear cylinder where a center of the colored piston (e.g., a reference area) is protected from contamination (e.g., dust and discoloration) via one or more gaskets. In additional embodiments, the reference element 1134 may include a planar surface as wide or wider than the chute and / or belt 1120 that can be pneumatically and / or electrically extend and retracted. In yet further embodiments, the reference element 1134 may include an element attached to a cleaning apparatus (e.g., a brush). In yet further embodiments, the reference element 1134 may be the commodity itself or elements inserted into the commodity. As is described in greater detail below, the sorter device 1102 may utilize the plurality of reference elements 1134 as a reference point for light perceived by the at least one detection system 1108. Furthermore, the sorter device 1102 may intermittently analyze colors of the reference elements 1134 being perceived by the one or more image sensors 1128 and utilize the perceived colors to adjust light being emitted by the plurality of illumination sources 1124 and / or settings of the one or more image sensors 1128.

[0207] In further embodiments, the at least one detection system 1108 may not include a plurality of reference elements 1134. Rather, in such embodiments, the one or more image sensors 1128 may be oriented to directly receive the light emitted by the plurality of illumination sources 1124. In other words, the one or more image sensors 1128 may be oriented to directly receive the light emitted by the plurality of illumination sources 1124 and light reflected from the stream 1122 of the bulk product 1116 due to the plurality of illumination sources 1124.

[0208] As is described briefly above, each of the infeed system 1106, the at least one detection system 1108, and the at least one ejector 1110 may be operably coupled to and at least partially operated by the system controller 1114. For example, the system controller 1114 may provide control signals to the infeed system 1106 to cause the infeed system 1106 to feed the bulk product 1116 to the chute and / or belt 1120 of the sorter device 1102 and to cause the chute and / or belt 1120 of the sorter device 1102 to generate a stream of the bulk product 1116. Furthermore, the system controller 1114 may provide control signals (e.g., the illumination control signals 132 (FIG. 1)) to the plurality of illumination sources 1124 and the one or more image sensors 1128 to control operation of the plurality of illumination sources 1124 and the one or more image sensors 1128. Furthermore, the system controller 1114 may receive image23205EPP data (e.g., the image signals 140 of FIG. 1) from the one or more image sensors 1128, analyze the image data, generate processed signals 122 (FIG.1) responsive to the image signal 140, and generate control signals for the at least one ejector 1110 based at least partially on the processed signals 122 (FIG.1). Moreover, the system controller 1114 may receive data from and may provide control signals to the plurality of intensity sensors 1130 and plurality of current sensors 1132. Additionally, the system controller 1114 may provide control signals to the plurality of reference elements 1134 in embodiments where the plurality of reference elements 1134 operates under control (e.g., piston and cylinder). The system controller 1114 is described in greater detail in regard to FIG. 14.

[0209] FIG. 12 is a block diagram illustrating a portion of the computing device 112 of FIG.1, according to some embodiments. As discussed above, the computing device 112 includes the one or more data storage devices 114, which includes the processed signals 122 stored thereon (e.g., the processed signals 122 , , and according to any of the approaches discussed above with reference to FIG. 2AFIG. 2E, FIG. 5A through FIG. 5E, FIG. 8A through FIG. 8E, or FIG. 9A through FIG. 9B).

[0210] The computing device 112 is also configured to implement an RGB color space 1202 including a red input channel R, a green input channel G, and a blue input channel B. The RGB color space 1202 is configured to generate a pseudo-color image 1206 responsive to mapping of the processed signals 122 to the RGB color space 1202. Specifically, the first processed signal is mapped to the red input channel R, the second processed signal is mapped to theinput channel G, and the third processed signal is mappedblue input channel B.

[0211] The computing device 112 is further configured to implement an image processor 1204. The image processor 1204 is configured to receive the pseudo-color image 1206 and process the pseudo-color image 1206. By way of non-limiting example, the computing device 112 and the imaging system 100 of FIG.1 may be used in a sorter device (e.g., the sorter device 1102 of FIG. 11), and the image processor 1204 may be used to determine how to sort bulk product (e.g., bulk product 1116 of FIG. 11) responsive to the pseudo-color image 1206.

[0212] FIG. 13 is a block diagram illustrating a portion of the computing device 112 of FIG. 1, that may be used with the approach discussed in FIG. 10A and FIG. 10B. As discussed23205EPP above, the computing device 112 includes the one or more data storage devices 114, which includes the processed signals 122 stored thereon (e.g., the processed signals 122 , , and according to any of the approach discussed above with reference to FIG. 10A and FIG. 10B.

[0213] The computing device 112 is also configured to implement an RGB color space 1302 including a red input channel R, a green input channel G, and a blue input channel B. The RGB color space 1302 is configured to generate a pseudo-color image 1306 responsive to mapping of the processed signals 122 to the RGB color space 1302. Specifically, the second processed signal is mapped to the green input channel G and the third processed signal is mapped to the red input channel R and to the blue input channel B.

[0214] The computing device 112 is further configured to implement an image processor 1304. The image processor 1304 is configured to receive the pseudo-color image 1306 and process the pseudo-color image 1306. By way of non-limiting example, the computing device 112 and the imaging system 100 of FIG.1 may be used in a sorter device (e.g., the sorter device 1102 of FIG. 11), and the image processor 1304 may be used to determine how to sort bulk product (e.g., bulk product 1116 of FIG. 11) responsive to the pseudo-color image 1306.

[0215] FIG. 14 is a schematic view of a computing device 1402, according to some embodiments. In some embodiments, system controller 1114 (FIG. 11) and / or the computing device 112 (FIG. 1) may include a computing device such as the computing device 1402 of FIG. 3. The computing device 1402 may include a communication interface 1404, a processor 1406, a memory 1408, a storage device 1410, an input / output device 1412, and a bus 1414.

[0216] In some embodiments, the processor 1406 includes hardware for executing instructions, such as those making up a computer program. As an example, and not by way of limitation, to execute instructions, the processor 1406 may retrieve (or fetch) the instructions from an internal register, an internal cache, the memory 1408, or the storage device 1410 and decode and execute them. The instructions may be configured to instruct the processor 1406 to perform operations discussed herein for the illumination control circuitry 130 and the signal processing circuitry 118. The instructions may also be configured to instruct the processor 1406 to perform at least a portion of the method 300 of FIG. 3 and / or the method 600 of FIG. 6. In23205EPP some embodiments, the processor 1406 may include one or more internal caches for data, instructions, or addresses. As an example, and not by way of limitation, the processor 1406 may include one or more instruction caches, one or more data caches, and one or more translation look aside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in the memory 1408 or the storage device 1410.

[0217] The memory 1408 may be coupled to the processor 1406. The memory 1408 may be used for storing data, metadata, and programs for execution by the processor(s). The memory 1408 may include one or more of volatile and non-volatile memories, such as Random- Access Memory (“RAM”), Read-Only Memory (“ROM”), a solid-state disk (“SSD”), Flash, Phase Change Memory (“PCM”), or other types of data storage. The memory 1408 may be internal or distributed memory.

[0218] The storage device 1410 may include storage for storing data or instructions. As an example, and not by way of limitation, storage device 1410 can comprise a non-transitory storage medium described above. The storage device 1410 may include a hard disk drive (HDD), Flash memory, an optical disc, a magneto-optical disc, magnetic tape, or a Universal Serial Bus (USB) drive or a combination of two or more of these. The storage device 1410 may include removable or non-removable (or fixed) media, where appropriate. The storage device 1410 may be internal or external to the computing storage device 1410. In one or more embodiments, the storage device 1410 is non-volatile, solid-state memory. In other embodiments, the storage device 1410 includes read-only memory (ROM). Where appropriate, this ROM may be mask programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM), or Flash memory or a combination of two or more of these.

[0219] The input / output device 1412 may allow an operator of the sorter device 1102 to provide input to, receive output from, and otherwise transfer data to and receive data from computing device 1402. The input / output device 1412 may include a mouse, a keypad or a keyboard, a joystick, a touch screen, a camera, an optical scanner, network interface, modem, other known I / O devices, or a combination of such I / O interfaces. The input / output device 1412 may include one or more devices for presenting output to an operator, including, but not limited to, a graphics engine, a display (e.g., a display screen), one or more output drivers (e.g., display23205EPP drivers), one or more audio speakers, and one or more audio drivers. In certain embodiments, the input / output device 1412 is configured to provide graphical data to a display for presentation to an operator. The graphical data may be representative of one or more graphical user interfaces and / or any other graphical content as may serve a particular implementation. The computing device 1402 and the input / output device 1412 may be utilized to display data (e.g., images and / or video data) regarding the sorting processes and adjustments to operating parameters of plurality of illumination sources 1124 (FIG.11) and / or one or more image sensors 1128 (FIG. 11) to maintain contact perceived light intensities.

[0220] The communication interface 1404 can include hardware, software, or both. The communication interface 1404 may provide one or more interfaces for communication (such as, for example, packet-based communication) between the computing device 1402 and one or more other computing devices or networks (e.g., a server). As an example, and not by way of limitation, the communication interface 1404 may include a network interface controller (NIC) or network adapter for communicating with an Ethernet or other wire-based network or a wireless NIC (WNIC) or wireless adapter for communicating with a wireless network, such as a WI-FI.

[0221] In some embodiments, the bus 1414 (e.g., a Controller Area Network (CAN) bus) may include hardware, software, or both that couples components of computing device 1402 to each other and to external components. EXAMPLES

[0222] A non-exhaustive, non-limiting list of examples follows. Not each of the examples listed below is explicitly and individually indicated as being combinable with all others of the examples listed below and examples and embodiments discussed above. It is intended, however, that these examples are combinable with all other examples and embodiments unless it would be apparent to one of ordinary skill in the art that the examples are not combinable.

[0223] Example 1: An imaging system, comprising: one or more first illumination sources, one or more second illumination sources, and one or more third illumination sources; and illumination control circuitry operably coupled to the one or more first illumination sources, the one or more second illumination sources, and the one or more third illumination sources, the23205EPP illumination control circuitry configured to: control the one or more first illumination sources to emit first incident EM radiation toward a target and maintain the one or more second illumination sources and the one or more third illumination sources in an off state during a first time period, the first incident EM radiation having a first spectral band; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a second time period, the second incident EM radiation having a second spectral band different from the first spectral band; and control the one or more first illumination sources, the one or more second illumination sources, and the one or more third illumination sources to emit the first incident EM radiation, the second incident EM radiation, and third incident EM radiation, respectively, toward the target in a third time period, the third incident EM radiation having a third spectral band different from the first spectral band and the second spectral band.

[0224] Example 2: The imaging system of Example 1, further comprising an image sensor configured to: generate a first image signal responsive to first reflected EM radiation received responsive to the first incident EM radiation during the first time period; generate a second image signal responsive to the first reflected EM radiation and second reflected EM radiation received responsive to the second incident EM radiation during the second time period; and generate a third image signal responsive to the first reflected EM radiation, the second reflected EM radiation, and third reflected EM radiation received responsive to the third incident EM radiation during the third time period.

[0225] Example 3: The imaging system of Example 2, further comprising signal processing circuitry configured to, responsive to the first image signal, the second image signal, and the third image signal, generate a first processed image signal proportional to the first reflected EM radiation, a second processed image signal proportional to the second reflected EM radiation, and a third processed image signal proportional to the third reflected EM radiation.

[0226] Example 4: The imaging system of Example 3, wherein the signal processing circuitry is configured to generate the first processed image signal by using the first image signal as the first processed image signal.23205EPP

[0227] Example 5: The imaging system according to any one of Examples 3 and 4, wherein the signal processing circuitry is configured to generate the second processed image signal by subtracting the first image signal from the second image signal to obtain the second processed image signal.

[0228] Example 6: The imaging system according to any one of Examples 3 and 4, wherein the signal processing circuitry is configured to generate the third processed image signal by subtracting the second image signal from the third image signal to obtain the third processed image signal.

[0229] Example 7: The imaging system according to any one of Examples 1-6, wherein the illumination control circuitry is configured to repeatedly cycle through the first time period, the second time period, and the third time period.

[0230] Example 8: The imaging system of Example 7, wherein the illumination control circuitry is configured to maintain the one or more first illumination sources emitting the first incident EM radiation through the repeated cycles through the first time period, the second time period, and the third time period.

[0231] Example 9: The imaging system according to any one of Examples 1-8, wherein the illumination control circuitry is configured to order the first time period, the second time period, and the third time period in sequence from the first time period to the second time period, and then to the third time period.

[0232] Example 10: The imaging system according to any one of Examples 1-8, wherein the illumination control circuitry is configured to order the first time period, the second time period, and the third time period in a sequence different from starting from the first time period, transitioning to the second time period, and then transitioning to the third time period.

[0233] Example 11: The imaging system according to any one of Examples 1-10, further comprising one or more fourth illumination sources, wherein the illumination control circuitry is configured to control the one or more fourth illumination sources to emit fourth incident EM radiation toward the target during the first time period, the second time period, and the third time period, the fourth incident EM radiation having a fourth spectral band different from the first spectral band, the second spectral band, and the third spectral band.23205EPP

[0234] Example 12: The imaging system of Example 11, wherein the first spectral band, the second spectral band, and the third spectral band are selected from an infrared spectral band and the fourth spectral band is a visible spectral band.

[0235] Example 13: The imaging system according to any one of Examples 1-6, wherein the illumination control circuitry is configured to: control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a fourth time period; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a fifth time period; and control the one or more first illumination sources, the one or more second illumination sources, and the one or more third illumination sources to emit the first incident EM radiation, the second incident EM radiation, and the third incident EM radiation, respectively, toward the target in a sixth time period.

[0236] Example 14: The imaging system according to any one of Examples 1-6, wherein the illumination control circuitry is configured to: control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a subsequent time period subsequent to the third time period; and control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a time period immediately following the subsequent time period.

[0237] Example 15: A sorting system, comprising: a plurality of sets of one or more illumination sources; and illumination control circuitry configured to operate the plurality of sets of one or more illumination sources in a step pattern with one or more first illumination sources turned on in a first time period, the one or more first illumination sources and one or more second illumination sources turned on in a second time period, and the one or more first illumination sources, the one or more second illumination sources, and one or more third illumination sources turned on in a third time period.23205EPP

[0238] Example 16: The sorting system of Example 15, further comprising an image sensor configured to capture a sub-image during each time period, wherein the illumination control circuitry is configured to repeatedly cycle through the first time period, the second time period, and the third time period and the image sensor is configured to capture a multispectral image each cycle through the first time period, the second time period, and the third time period.

[0239] Example 17: The sorting system of Example 15, wherein the step pattern is a zig- zag step pattern wherein the illumination control circuitry is configured to step down the plurality of sets of one or more illumination sources over multiple periods of time from all of the plurality of sets of one or more illumination sources being turned on to only the one or more first illumination sources being maintained on.

[0240] Example 18: The sorting system of Example 17, further comprising an image sensor configured to capture a sub-image during each time period.

[0241] Example 19: The sorting system according to each of Examples 17 and 18, further comprising signal processing circuitry configured to generate processed image signals responsive to image signals captured during each time period, the processed image signals corresponding to individual spectral bands of each set of the plurality of sets of one or more illumination sources.

[0242] Example 20: A method of operating an imaging system, the method comprising: operating one or more first illumination sources in an on state during a first time period; capturing a first image signal in the first time period; operating the one or more first illumination sources and one or more second illumination sources in the on state during a second time period; capturing a second image signal in the second time period; operating the one or more first illumination sources, the one or more second illumination sources, and one or more subsequent illumination sources in the on state during a subsequent time period; capturing a subsequent image signal in the subsequent time period; generating a first processed image signal to be the first image signal; generating a second processed image signal to be the first image signal subtracted from the second image signal; and generating a subsequent processed image signal to be an immediately previous image signal previous to the subsequent image signal subtracted from the subsequent image signal.23205EPP

[0243] Example 21: An imaging system, comprising: one or more first illumination sources, one or more second illumination sources, and one or more third illumination sources; and illumination control circuitry operably coupled to the one or more first illumination sources, the one or more second illumination sources, and the one or more third illumination sources, the illumination control circuitry configured to: control the one or more first illumination sources to emit first incident EM radiation toward a target and maintain the one or more second illumination sources and the one or more third illumination sources in an off state during a first time period, the first incident EM radiation having a first spectral band; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a second time period, the second incident EM radiation having a second spectral band different from the first spectral band; and control the one or more first illumination sources and the one or more third illumination sources to emit the first incident EM radiation and third incident EM radiation, respectively, toward the target and maintain the one or more second illumination sources in the off state during a third time period, the third incident EM radiation having a third spectral band different from the first spectral band and the second spectral band.

[0244] Example 22: The imaging system of Example 21, further comprising an image sensor configured to: generate a first image signal responsive to first reflected EM radiation received responsive to the first incident EM radiation during the first time period; generate a second image signal responsive to the first reflected EM radiation and second reflected EM radiation received responsive to the second incident EM radiation during the second time period; and generate a third image signal responsive to the first reflected EM radiation and third reflected EM radiation received responsive to the third incident EM radiation during the third time period.

[0245] Example 23: The imaging system of Example 22, further comprising signal processing circuitry configured to, responsive to the first image signal, the second image signal, and the third image signal, generate a first processed image signal proportional to the first reflected EM radiation, a second processed image signal proportional to the second reflected23205EPP EM radiation, and a third processed image signal proportional to the third reflected EM radiation.

[0246] Example 24: The imaging system of Example 23, wherein the signal processing circuitry is configured to generate the first processed image signal by using the first image signal as the first processed image signal.

[0247] Example 25: The imaging system according to any one of Examples 23 and 24, wherein the signal processing circuitry is configured to generate the second processed image signal by subtracting the first image signal from the second image signal to obtain the second processed image signal.

[0248] Example 26: The imaging system according to any one of Examples 23 and 24, wherein the signal processing circuitry is configured to generate the third processed image signal by subtracting the first image signal from the third image signal to obtain the third processed image signal.

[0249] Example 27: The imaging system according to any one of Examples 21-26, wherein the illumination control circuitry is configured to repeatedly cycle through the first time period, the second time period, and the third time period.

[0250] Example 28: The imaging system of Example 27, wherein the illumination control circuitry is configured to maintain the one or more first illumination sources emitting the first incident EM radiation through the repeated cycles through the first time period, the second time period, and the third time period.

[0251] Example 29: The imaging system according to any one of Examples 21-28, wherein the illumination control circuitry is configured to order the first time period, the second time period, and the third time period in sequence from the first time period to the second time period, and then to the third time period.

[0252] Example 30: The imaging system according to any one of Examples 21-28, wherein the illumination control circuitry is configured to order the first time period, the second time period, and the third time period in a sequence different from starting from the first time period, transitioning to the second time period, and then transitioning to the third time period.

[0253] Example 31: The imaging system according to any one of Examples 21-30, further comprising one or more fourth illumination sources, wherein the illumination control circuitry23205EPP is configured to control the one or more fourth illumination sources to emit fourth incident EM radiation toward the target during the first time period, the second time period, and the third time period, the fourth incident EM radiation having a fourth spectral band different from the first spectral band, the second spectral band, and the third spectral band.

[0254] Example 32: The imaging system of Example 31, wherein the first spectral band, the second spectral band, and the third spectral band are selected from an infrared spectral band and the fourth spectral band is a visible spectral band.

[0255] Example 33: The imaging system according to any one of Examples 21-26, wherein the illumination control circuitry is configured to: control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a fourth time period; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a fifth time period; and control the one or more first illumination sources and the one or more third illumination sources to emit the first incident EM radiation and the third incident EM radiation, respectively, toward the target and maintain the one or more second illumination sources in the off state during a sixth time period.

[0256] Example 34: The imaging system according to any one of Examples 21-26, wherein the illumination control circuitry is configured to: control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a subsequent time period subsequent to the third time period; and control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a time period immediately following the subsequent time period.

[0257] Example 35: A sorting system, comprising: a plurality of sets of one or more illumination sources; and illumination control circuitry configured to operate the plurality of sets of one or more illumination sources with one or more first illumination sources turned on23205EPP in a first time period, the one or more first illumination sources and one or more second illumination sources turned on in a second time period, and the one or more first illumination sources and one or more third illumination sources turned on in a third time period.

[0258] Example 36: The sorting system of Example 35, further comprising an image sensor configured to capture a sub-image during each time period, wherein the illumination control circuitry is configured to repeatedly cycle through the first time period, the second time period, and the third time period and the image sensor is configured to capture a multispectral image each cycle through the first time period, the second time period, and the third time period.

[0259] Example 37: The sorting system of Example 35, wherein the illumination control circuitry is configured to cycle back through the plurality of sets of one or more illumination sources from a last of the plurality of sets of one or more illumination sources over multiple periods of time to a second set of the plurality of sets of one or more illumination sources then to only the one or more first illumination sources being maintained on.

[0260] Example 38: The sorting system of Example 37, further comprising an image sensor configured to capture a sub-image during each time period.

[0261] Example 39: The sorting system according to any one of Examples 37 and 38, further comprising signal processing circuitry configured to generate processed image signals responsive to image signals captured during each time period, the processed image signals corresponding to individual spectral bands of each set of the plurality of sets of one or more illumination sources.

[0262] Example 40: A method of operating an imaging system, the method comprising: operating one or more first illumination sources in an on state during a first time period; capturing a first image signal in the first time period; operating the one or more first illumination sources and one or more second illumination sources in the on state during a second time period; capturing a second image signal in the second time period; operating the one or more first illumination sources and one or more subsequent illumination sources in the on state during a subsequent time period; capturing a subsequent image signal in the subsequent time period; generating a first processed image signal to be the first image signal; generating a second processed image signal to be the first image signal subtracted from the second image23205EPP signal; and generating a subsequent processed image signal to be the first image signal subtracted from the subsequent image signal.

[0263] Example 41: A sorting device including the imaging system according to any one of examples 1-14 and 21-34. CONCLUSION

[0264] As used in the present disclosure, the terms “module” or “component” may refer to specific hardware implementations configured to perform the actions of the module or component and / or software objects or software routines that may be stored on and / or executed by general purpose hardware (e.g., computer-readable media, processing devices, etc.) of the computing system. In some embodiments, the different components, modules, engines, and services described in the present disclosure may be implemented as objects or processes that execute on the computing system (e.g., as separate threads). While some of the system and methods described in the present disclosure are generally described as being implemented in software (stored on and / or executed by general purpose hardware), specific hardware implementations or a combination of software and specific hardware implementations are also possible and contemplated.

[0265] As used in the present disclosure, the term “combination” with reference to a plurality of elements may include a combination of all the elements or any of various different subcombinations of some of the elements. For example, the phrase “A, B, C, D, or combinations thereof” may refer to any one of A, B, C, or D; the combination of each of A, B, C, and D; and any subcombination of A, B, C, or D such as A, B, and C; A, B, and D; A, C, and D; B, C, and D; A and B; A and C; A and D; B and C; B and D; or C and D.

[0266] Terms used in the present disclosure and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes, but is not limited to,” etc.).

[0267] Additionally, if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no23205EPP such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations.

[0268] In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” or “one or more of A, B, and C, etc.” is used, in general such a construction is intended to include A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together, etc.

[0269] Further, any disjunctive word or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” should be understood to include the possibilities of “A” or “B” or “A and B.”

[0270] While the present disclosure has been described herein with respect to certain illustrated embodiments, those of ordinary skill in the art will recognize and appreciate that the present invention is not so limited. Rather, many additions, deletions, and modifications to the illustrated and described embodiments may be made without departing from the scope of the invention as hereinafter claimed along with their legal equivalents. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventor.23205EPP

[0271] All references cited herein are incorporated herein in their entireties. If there is a conflict between definitions herein and in an incorporated reference, the definition herein shall control.

Claims

23205EPP CLAIMS What is claimed is:

1. An imaging system, comprising: one or more first illumination sources, one or more second illumination sources, and one or more third illumination sources; and illumination control circuitry operably coupled to the one or more first illumination sources, the one or more second illumination sources, and the one or more third illumination sources, the illumination control circuitry configured to: control the one or more first illumination sources to emit first incident EM radiation toward a target and maintain the one or more second illumination sources and the one or more third illumination sources in an off state during a first time period, the first incident EM radiation having a first spectral band; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a second time period, the second incident EM radiation having a second spectral band different from the first spectral band; and control the one or more first illumination sources and the one or more third illumination sources to emit the first incident EM radiation and third incident EM radiation, respectively, toward the target and maintain the one or more second illumination sources in the off state during a third time period, the third incident EM radiation having a third spectral band different from the first spectral band and the second spectral band.

2. The imaging system of claim 1, further comprising an image sensor configured to: generate a first image signal responsive to first reflected EM radiation received responsive to the first incident EM radiation during the first time period; generate a second image signal responsive to the first reflected EM radiation and second reflected EM radiation received responsive to the second incident EM radiation during the second time period; and23205EPP generate a third image signal responsive to the first reflected EM radiation and third reflected EM radiation received responsive to the third incident EM radiation during the third time period.

3. The imaging system of claim 2, further comprising signal processing circuitry configured to, responsive to the first image signal, the second image signal, and the third image signal, generate a first processed image signal proportional to the first reflected EM radiation, a second processed image signal proportional to the second reflected EM radiation, and a third processed image signal proportional to the third reflected EM radiation.

4. The imaging system of claim 3, wherein the signal processing circuitry is configured to generate the first processed image signal by using the first image signal as the first processed image signal.

5. The imaging system according to any one of claims 3 and 4, wherein the signal processing circuitry is configured to generate the second processed image signal by subtracting the first image signal from the second image signal to obtain the second processed image signal.

6. The imaging system according to any one of claims 3 and 4, wherein the signal processing circuitry is configured to generate the third processed image signal by subtracting the first image signal from the third image signal to obtain the third processed image signal.

7. The imaging system according to any one of claims 1-6, wherein the illumination control circuitry is configured to repeatedly cycle through the first time period, the second time period, and the third time period.

8. The imaging system of claim 7, wherein the illumination control circuitry is configured to maintain the one or more first illumination sources emitting the first incident EM radiation through the repeated cycles through the first time period, the second time period, and the third time period.

9. The imaging system according to any one of claims 1-8, wherein the illumination control circuitry is configured to order the first time period, the second time period, and the23205EPP third time period in sequence from the first time period to the second time period, and then to the third time period.

10. The imaging system according to any one of claims 1-8, wherein the illumination control circuitry is configured to order the first time period, the second time period, and the third time period in a sequence different from starting from the first time period, transitioning to the second time period, and then transitioning to the third time period.

11. The imaging system according to any one of claims 1-10, further comprising one or more fourth illumination sources, wherein the illumination control circuitry is configured to control the one or more fourth illumination sources to emit fourth incident EM radiation toward the target during the first time period, the second time period, and the third time period, the fourth incident EM radiation having a fourth spectral band different from the first spectral band, the second spectral band, and the third spectral band.

12. The imaging system of claim 11, wherein the first spectral band, the second spectral band, and the third spectral band are selected from an infrared spectral band and the fourth spectral band is a visible spectral band.

13. The imaging system according to any one of claims 1-6, wherein the illumination control circuitry is configured to: control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a fourth time period; control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a fifth time period; and control the one or more first illumination sources and the one or more third illumination sources to emit the first incident EM radiation and the third incident EM radiation, respectively, toward the target and maintain the one or more second illumination sources in the off state during a sixth time period.23205EPP 14. The imaging system according to any one of claims 1-6, wherein the illumination control circuitry is configured to: control the one or more first illumination sources and the one or more second illumination sources to emit the first incident EM radiation and the second incident EM radiation, respectively, toward the target and maintain the one or more third illumination sources in the off state during a subsequent time period subsequent to the third time period; and control the one or more first illumination sources to emit the first incident EM radiation toward the target and maintain the one or more second illumination sources and the one or more third illumination sources in the off state during a time period immediately following the subsequent time period.

15. A method of operating an imaging system, the method comprising: operating one or more first illumination sources in an on state during a first time period; capturing a first image signal in the first time period; operating the one or more first illumination sources and one or more second illumination sources in the on state during a second time period; capturing a second image signal in the second time period; operating the one or more first illumination sources and one or more subsequent illumination sources in the on state during a subsequent time period; capturing a subsequent image signal in the subsequent time period; generating a first processed image signal to be the first image signal; generating a second processed image signal to be the first image signal subtracted from the second image signal; and generating a subsequent processed image signal to be the first image signal subtracted from the subsequent image signal.

Images