Multiband imaging spectrometer

Abstract

The present disclosure relates to a multi-band imaging spectrometer. A system includes a detector and at least one optical component that directs light to the detector. The system also includes a spatially varying spectral filter positioned in the optical system and having at least two bandpass regions: a first bandpass region that passes light of a first wavelength range and a second bandpass region that passes light of a second wavelength range different from the first wavelength range. The system also includes circuitry configured to perform a first transform operation on light of the first wavelength detected by the detector and a second transform operation on light of the second wavelength detected by the detector.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 734,354, filed December 16, 2024, the entire disclosure of which is incorporated herein by reference. Summary of the Invention

[0002] In some aspects, the technology described herein relates to a system comprising: a detector positioned at an end of an optical path; a set of optical components positioned along the optical path such that the set of optical components directs light from the scene to the detector, the set of optical components including an interferometer configured to create a set of interferograms; a spatially variable spectral filter positioned along the optical path and configured to expose different regions of the detector to different spectral bands of light originating from the scene; and a processor communicatively coupled to the detector and configured to process the set of interferograms detected by the detector in a manner that extracts spectral information from the set of interferograms.

[0003] In some aspects, the technology described herein relates to a method of manufacturing a multi-band imaging spectrometer device, the method comprising: coupling a detector to a circuit configured to process an interferogram generated by the detector; assembling an interferometer in optical communication with the detector, the interferometer being configured to direct modulated light to the detector; mounting a spatially varied spectral filter near the detector and the interferometer, the filter being adapted to expose different regions of the detector to different spectral bands of the modulated light; and arranging a set of optical components, including the interferometer and the spatially varied spectral filter, such that light from the scene passes through the interferometer and the filter before reaching the detector.

[0004] In some aspects, the technology described herein relates to a system comprising: a spectrometer including: a detector positioned at an end of an optical path; a set of optical components positioned along the optical path such that the set of optical components directs light from the scene to the detector; the set of optical components including an interferometer configured to create a set of interferograms; a spatially varying spectral filter positioned along the optical path and configured to expose different regions of the detector to different spectral bands of light originating from the scene; a processor communicatively coupled to the detector and configured to process the set of interferograms detected by the detector in a manner that extracts spectral information from the set of interferograms; and a mounting interface configured to attach the spectrometer to a remote sensing platform.

[0005] Based on the general principles described herein, any feature of the embodiments described herein can be used in combination with each other. These and other embodiments, features, and advantages will be more fully understood upon reading the following detailed description in conjunction with the accompanying drawings and claims. Attached Figure Description

[0006] The accompanying drawings illustrate several exemplary embodiments and are part of the specification. Together with the following description, these drawings illustrate and explain various principles of this disclosure.

[0007] Figure 1A The spectral distribution of the detector's quantum efficiency is shown.

[0008] Figure 1B An example of a multispectral imaging system is shown.

[0009] Figure 2A A block diagram of a conventional solution with three optics and detectors is shown.

[0010] Figure 2B A block diagram of an embodiment of the present disclosure is shown, in which the detector is combined in an optical branch.

[0011] Figure 3 An example of where a filter can be located according to an embodiment of the present disclosure is shown.

[0012] Figure 4 The blackbody radiation of the human body at 20°C is shown.

[0013] Figure 5 The measurement of ground features using the embodiments disclosed herein is illustrated.

[0014] Figure 6 A method for manufacturing a multispectral imaging system according to embodiments disclosed herein is illustrated.

[0015] Throughout the accompanying drawings, the same reference numerals and descriptions indicate similar but not necessarily identical elements. While the exemplary embodiments described herein are susceptible to various modifications and alternatives, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, the exemplary embodiments described herein are not intended to be limited to the particular forms disclosed. Rather, this disclosure covers all modifications, equivalents, and alternatives falling within the scope of the appended claims. Detailed Implementation

[0016] This disclosure relates to multi-band imaging spectrometer systems, and more specifically, to systems and methods for simultaneously acquiring multiple spectral bands using a single detector. Traditional imaging device architectures typically involve separate optical chains and detectors for each spectral band, increasing complexity, size, and cost. The disclosed embodiments address this complexity by employing spatially varying spectral filters in conjunction with interferometers, allowing different regions of a single detector to be exposed to different spectral bands. This approach simplifies optical design, reduces hardware requirements, and improves the efficiency and practicality of multi-band spectral imaging for applications such as remote sensing, atmospheric monitoring, and Earth observation from airborne, spaceborne, and / or ground-based platforms.

[0017] Photon detectors begin to respond from their specific cutoff wavelength and typically extend to shorter wavelengths, such as... Figure 1A Figure 100 shows the quantum efficiency of an example long-wave infrared (LWIR) detector with a cutoff wavelength of 13.5 µm. An example of a multi-band imaging spectrometer using such detectors is a Fourier transform spectrometer. Fourier transform spectrometers can decompose the entire instrument bandwidth into multiple bands because a particular detector responds only within a specific spectral range, such as... Figure 1B As shown. In some cases, they divide the entire instrument bandwidth into separate bands to reduce the number of visible photons in each band, thereby reducing the measurement noise (shot noise) associated with the detected photons. This is typically achieved by introducing a dichroic beam splitter in the optical components ( Figure 1B To achieve this, use BS1 and BS2 in the code, such as... Figure 1B The optical system 110 shown in the figure enables the system to direct selected wavelengths to separate optical components dedicated to those wavelengths.

[0018] like Figure 1B As shown, front optics 114 collects light from the scene, such as reflected and emitted radiation from the Earth. This light is then guided into an interferometer, which modulates the collected light. The light then passes through beamsplitter BS1, which splits the light into different spectral bands. The reflected portion is collected at LWIR detector 120 (LWDET) and mid-wave infrared (MW DET) detector 122 (via a second beamsplitter BS2), while the transmitted portion is collected at short-wave infrared (SWIR) detector 124 (SW DET). In this example, each of the separated spectral bands is focused onto its corresponding imaging detector (DET) by a set of objectives (OBJ). Figure 1B These are examples of the types of complexity that can be involved in architectures with different optical paths and detectors.

[0019] The embodiments disclosed herein are applicable to the field of commercial aerospace instrumentation, such as weather detection using infrared light. Such applications may involve measuring infrared light with a high signal-to-noise ratio in the 4 µm to 15 µm range. Conventional detectors divide this spectral range into three bands and have three detector chains. These bands are commonly referred to as short wave (SW), medium wave (MW), and long wave (LW). For example, the SW, MW, and LW bands can span spectral ranges of 4 µm to 5.6 µm, 5.6 µm to 8.7 µm, or 8.7 µm to 14 µm, but other ranges may also be used.

[0020] An example of this type of instrument is in Figure 2A The image is shown as a multispectral imager 210, in which light from scene 212 first enters a front optics 216, which is responsible for collecting and collimating the incident light. The front optics 216 can also be coupled to a radiometric reference 214, which provides a known calibration signal to ensure the accuracy and reliability of the spectrometer measurements. After passing through the front optics, the light proceeds to an interferometer 218. The interferometer 218 modulates the light by creating an optical path difference, encoding spectral information into an interferogram.

[0021] After interferometer modulation, the light is split into three distinct optical paths, each corresponding to a different spectral band. These paths are managed by three sets of aft optics: aft optics 220, 222, and 224. Each set of aft optics is designed to focus the modulated light and guide it to a specific detector optimized for a particular spectral range. Aft optics 220 guides the light to a short-wavelength detector 226, aft optics 222 guides the light to a mid-wavelength detector 228, and aft optics 224 guides the light to a long-wavelength detector 230. This configuration allows the system to simultaneously capture and analyze spectral information in the short-wavelength, mid-wavelength, and long-wavelength bands; however, the multiple optical paths introduce complexity, cost, and weight issues.

[0022] Figure 2B An example of a multispectral imager 240 configured according to embodiments of the present disclosure is shown. Figure 2B In this system, the multispectral imager 240 operates by first receiving light from scene 242. This light is collected and collimated by a front optics device 246, which guides the incident radiation along the optical path. The front optics device 246 can also be coupled to a radiometric reference 244, which provides a known calibration signal to ensure the accuracy and reliability of the instrument's measurements. After passing through the front optics, the light enters an interferometer 248. The interferometer 248 modulates the light by introducing an optical path difference, thereby encoding spectral information into an interferogram.

[0023] Once the light is modulated by the interferometer, it is guided through a set of rear optics 250. The rear optics 250 focus the modulated light and relay it to a broadband detector 252. Unlike conventional systems that split the light into multiple paths for individual detectors, this configuration allows the broadband detector 252 to simultaneously receive and record spectral information across a wide range of wavelengths. The result is a simplified system that captures comprehensive multispectral data using a single optical chain and detector, simplifying instrument design and reducing hardware complexity.

[0024] Embodiments of this disclosure provide a potential solution that uses a single detector chain to cover two, three, or more bands. Embodiments of this disclosure can be implemented in ground systems, satellite systems, spacecraft-borne systems, or in any other suitable type or form of system.

[0025] Some embodiments of this disclosure combine imaging Fourier transform spectroscopy (FTS) with a spatially varied spectral filter positioned at an intermediate image plane. Figure 3 An example of a rear optics 300 for this configuration is shown, wherein light passes from a pupil 302 through optical components 304, 306, 308, and 310 to generate an image on detector 320. An example spatially varying spectral filter 312 is characterized by three bandpass regions: short-wave 314, mid-wave 316, and long-wave 318. By placing the spatially varying spectral filter at position 325, spectral filtering occurs in the beam re-imaged on the detector, resulting in three detector segments, with only one band incident.

[0026] Spatially variable spectral filters can be placed on or near the image plane in the optical path. For example, the filter can be placed near the detector, or at any other location that enables it to perform spectral filtering.

[0027] In some examples, the embodiments described herein provide better noise performance than conventional systems, especially in shorter wavelength bands where otherwise unwanted long-wavelength photons would overwhelm the detector and generate noise, thus degrading performance. For example... Figure 4 As shown in graph 400, this is especially true for near-room-temperature objects that emit more radiation at longer wavelengths.

[0028] Some implementations can be combined with image motion compensation mechanisms to capture scenes over a longer period of time, such as when the aircraft equipped with the instrument is moving forward, whether it is a spacecraft or an aircraft.

[0029] Figure 5The illustration depicts a scenario where an aircraft is moving vertically toward the top of the image, and for clarity, successive views are shifted laterally to the right. This can be seen in View 1, View 2, and View... Figure 3 Ground features were captured spatially and spectrally from three bands of interest (shortwave, mediumwave, and longwave). Complete spatial and spectral information can be obtained from View 1, View 2, and View 3. Figure 3 The data was stitched back together during post-processing at the start of the measurement.

[0030] The quality factor of a Fourier transform spectroradiometer (or any spectroradiometer) that represents its sensitivity can be expressed as its... Noise equivalent spectral radiance , is defined as such that the measured signal-to-noise ratio (SNR) is given by the following formula: {Equation 1} in It is the spectral radiance of the source measured by a spectroradiometer, and It is the wave number of light, i.e., wavelength. The reciprocal of the frequency. The wavenumber is similar to the frequency and is a more natural scale than the wavelength of a Fourier transform spectrometer.

[0031] The lower the NESR, the more sensitive the spectroradiometer, because it can detect lower levels of radiation. NESR can also be considered as the expected statistical variation or standard deviation of continuous measurements by the instrument, expressed in radiation. NESR is calculated using Equation 2. {Equation 2}

[0032] in This is the noise-equivalent spectral power of the photodetector used in a spectroradiometer, and its unit is indicated in square brackets. It is the efficiency of the spectroradiometer (see Formula 4) or its ability to sense incident light. The range is from 0 to 1, where 1 represents ideal efficiency. It refers to the optical light-gathering rate of a spectroradiometer or its ability to receive and utilize radiation from a light source, and This is the spectral resolution of the spectroradiometer, representing the spectral width of the bins it divides light into. It is the observation time measured.

[0033] Noise equivalent power (NEP) is a measure of the sensitivity of a photodetector. High-performance detectors can be photodetectors, such as photon detectors. In a perfect photon detector, one photon generates one charge, which can be processed and counted by circuitry. A perfect photon detector should be characterized by a unit quantum efficiency (i.e., each incident photon generates one electron, regardless of its wavelength). Realistic detectors are characterized by quantum efficiencies below 1, such as... Figure 1A The provided example illustrates this. Furthermore, real-world photon detectors exhibit a cutoff point where they can no longer detect photons and generate electrons with wavelengths longer than the transition point. This is evident in... Figure 1A Examples with wavelengths greater than ~16 µm are also provided.

[0034] The ability of a photon detector to convert photons into electrical charges varies with wavelength (and wavenumber) and can also be expressed as responsivity. It represents the number of charges created per unit energy of an incident photon, expressed in units of... .

[0035] Noise equivalent power (NEP) is defined as the signal power with a signal-to-noise ratio of 1 within a 1 Hz output bandwidth. Noise equivalent power (NEP) can be written as: {Equation 3}

[0036] in This represents the current noise in the photodetector and the equivalent current noise caused by the circuitry downstream of the photodetector. It refers to the responsivity of the photodetector. It's photon noise. Due to the particle nature of light, statistical noise (shot noise) exists in any beam of light. This noise is equal to... ,in This represents the total photocurrent. This is equivalent current electronic noise. The noise from the electronic circuitry located after the photodetector can be converted to units of... The noise is determined by dividing the voltage noise by the unit. Electrical gain.

[0037] The efficiency of a spectroradiometer is given by the following formula. {Equation 4}

[0038] in It is the overall transmittance of the spectroradiometer, indicating how much light is not reflected or scattered by the optical elements in the spectroradiometer, and It is the modulation efficiency of a Fourier transform spectroradiometer (interferometer), that is, its modulation wavenumber is... The ability of light.

[0039] One example of improving the noise performance of a given spectroradiometer is increasing or maximizing the denominator in Equation 2. Some embodiments may involve increasing or maximizing the spectroradiometer efficiency ϵ(σ) and optical spread Θ, for example, by improving the quality and size of the optical components used in the instrument. The spectral resolution Δσ varies because some embodiments may not allow Δσ to be increased beyond a certain value necessary to measure the observed phenomenon. For example, we might need a spectral resolution higher than 1 cm⁻¹ to be able to resolve two spectral absorption lines caused by a chemical reagent, assuming this is the goal of the spectrometer system. Increasing Δσ beyond this value can improve the SNR of the collected spectrum, but will reduce our ability to distinguish important features of interest. Finally, the observation time will be pushed to a maximum value, but it is usually limited to a specific value, such as the time interval available in one natural period of the observed phenomenon or the time interval set by the time resolution required by the experiment of interest.

[0040] In addition to these improvements, some embodiments may also involve reducing or minimizing the numerator in Equation 2 to reduce the noise equivalent power (NEP), thereby minimizing the instrument noise equivalent spectral radiance (NESR). According to Equation 3, this can be achieved by utilizing electronic devices with low electronic noise. Since the total noise of the system is the square root of the sum of squares, there exists an electronic noise level above which its contribution is negligible. When this is achieved, we say that the instrument is "photon noise limited," meaning it is noise-limited by... It is controlled. According to Equation 3, this occurs when electronic noise is 3 to 5 times lower than photon noise, so electronic noise accounts for only 4% to 11% of the total noise.

[0041] When an instrument is "photon noise limited," an improvement to the system can be achieved by increasing its photon collection capability, such as by opening the instrument aperture or field of view, which increases the optical spread Θ. Increasing the optical spread increases the measured signal, but also increases the associated photon noise. However, since the signal increases proportionally to the light collection rate, and the photon noise... As the square root of the light-gathering power increases, this action will still produce a net SNR gain. Increasing the optical extension Θ is costly because several components in the instrument need to be scaled up proportionally, such as the diameter of the lens.

[0042] Fourier transform spectrometers are called "multiplexed" instruments because they do not disperse or reject light, unlike diffraction gratings, prisms, or bandpass filters. Instead, all light entering a Fourier transform spectrometer is directed to its photodetector. Fourier transform spectrometers can time-encode spectral information by modulating light to distinguish different wavelengths. Each wavelength in a Fourier transform spectrometer is affected by cosine modulation, the frequency of which is inversely proportional to its wavelength. A simple Fourier transform of the natural Fourier transform spectrometer signal directly produces the spectrum of the analyzed light. A key characteristic of Fourier transform spectrometers is that, on average, all light illuminates its photodetector.

[0043] This highlights another achievable improvement to enhance the SNR of Fourier transform spectroradiometers. As achieved by the systems and methods described herein, reducing the bandwidth of the light illuminating the photodetector of the spectroradiometer can improve the SNR of the light contained within the spectral bandpass. This bandwidth reduction results in a decrease in photocurrent. This effect also reduces photon noise. This reduces NEP. While doing so, some embodiments may involve not measuring spectral regions outside the reduced bandwidth. Therefore, instead of simply reducing bandwidth, some embodiments may divide a given bandwidth into a number of bands, creating these separated bands using individual photodetectors and optical chains, as described above. Figure 1B As shown. Then, each band can have reduced photon noise while maintaining a good signal response within the band. The final spectrum of such instruments can be reconstructed by stitching together portions of the spectrum from each band.

[0044] In some examples, the system includes a detector and at least one optical component that directs light to the detector. Any suitable detector and optical configuration can be used (e.g., a...). Figure 3 (As shown in the configuration). The system also includes a spatially variable spectral filter positioned at or near any image plane in the optical system, and having at least two bandpass regions: a first bandpass region that transmits light of a first wavelength range, and a second bandpass region that transmits light of a second wavelength range different from the first wavelength range. These wavelength ranges can be any suitable wavelength. The system may also include circuitry configured to perform a first conversion operation on light of the first wavelength detected by the detector, and a second conversion operation on light of the second wavelength detected by the detector. The circuitry may include integrated circuits, application-specific integrated circuits, mixed-signal circuits, accelerator circuits, and / or any other suitable type or form of processing device.

[0045] In some examples, the circuitry can be a processor configured to combine spatial and spectral information collected from different regions of the detector. Because spatially varying spectral filters expose different regions of the detector to different spectral bands, the processor can integrate this data to create a single synthetic image containing multi-band spectral information. This synthetic image allows users to analyze features across multiple wavelengths in a unified format, enhancing the system's utility in remote sensing and scientific analysis.

[0046] In some examples, the circuitry can be a processor configured to process the data collected by the detector by performing a Fourier transform on each interferogram. As the system runs, the interferometer generates a set of interferograms—one for each region or pixel of the detector. By applying a Fourier transform to each interferogram, the processor transforms the raw data into a detailed spectral profile for each region of the detector. This enables high-resolution multi-band spectral analysis, providing the user with rich spectral information for every part of the observed scene.

[0047] Figure 6 An exemplary method for manufacturing a multi-band imaging spectrometer system is illustrated. Step 610 involves coupling a detector to the multispectral imager, a process that can be performed in various ways depending on the specific application, instrument architecture, and desired spectral performance. The detector can be physically mounted to the imager's optical mount using mechanical fasteners, vibration-damping brackets, or precision alignment fixtures to ensure optimal positioning on the focal plane. In some embodiments, the detector can be integrated into a modular case or housing, allowing for easy replacement or upgrades, or it can be thermally coupled to a cooling system—such as a thermoelectric cooler, a cryogenic Dewar flask, or a Stirling cooler—to maintain a stable operating temperature and reduce thermal noise.

[0048] Numerous detector types are available for multispectral imagers, and the choice can be based on the target spectral band and sensitivity requirements. For example, detectors can be mercury cadmium telluride (MCT) focal plane arrays for infrared imaging, silicon charge-coupled devices (CCDs) or complementary metal-oxide-semiconductor (CMOS) arrays for visible and near-infrared wavelengths, or indium gallium arsenide (InGaAs) arrays for short-wave infrared detection. Detectors can be sensitive to a wide range of wavelengths, such as 0.4 µm to 1.0 µm for visible-near-infrared light, 1.0 µm to 2.5 µm for short-wave infrared light, 3 µm to 5 µm for mid-wave infrared light, or 8 µm to 14 µm for long-wave infrared light. In some cases, detectors can be hybrid arrays capable of simultaneously detecting multiple spectral regions, or they can be divided into multiple regions, each optimized for a specific wavelength range.

[0049] The detector is electrically coupled to associated circuitry, which may include a preamplifier, analog-to-digital converter, and signal processing module. This circuitry can also be coupled locally or remotely to a computer system for advanced data analysis, calibration, and image reconstruction. The computer system can execute algorithms for spectral decomposition, feature extraction, atmospheric correction, or machine learning-based classification, enabling the multispectral imager to deliver actionable information for applications such as weather detection, remote sensing, environmental monitoring, agricultural assessment, or defense surveillance. This flexible coupling of the detector and circuitry with the computer system ensures that the multispectral imager can be adapted to a variety of operational scenarios and scientific objectives.

[0050] Step 620 involves assembling the interferometer into the multispectral imager, enabling it to communicate optically with the detector. This process begins with selecting a suitable interferometer design, such as a Michelson interferometer, a Mach-Zehnder interferometer, or a Sagnac interferometer, depending on the desired spectral resolution, wavelength range, and system architecture. An interferometer typically consists of a beam splitter, one or more mirrors (at least one of which is movable to introduce a variable optical path difference), and supporting mechanical structures for precise alignment and stability.

[0051] To couple the interferometer into the multispectral imager, the interferometer is positioned along the optical path between the front optics and the detector. An alignment beam splitter, receiving collimated or focused light from the front optics, splits the incident beam into two or more paths. Mirrors are mounted on precision translational or rotational platforms and / or actuators, allowing controlled movement to modulate the optical path difference and generate an interferogram. The recombined light exits the interferometer and is guided towards the detector, either directly or through additional optical elements such as relay lenses or spatially varied spectral filters.

[0052] Mechanical coupling between the interferometer and the imager can be achieved using rigid mounting brackets, vibration-isolated platforms, or moving supports to ensure stable alignment and minimize environmental interference. Optical coupling may involve using alignment lasers, reference marks, or active feedback systems to maintain optimal optical throughput and minimize losses. In some embodiments, the interferometer can be integrated into a modular optical rig, allowing for easy installation, removal, or replacement as needed.

[0053] For example, a Michelson interferometer can be assembled by mounting a beam splitter at a 45-degree angle to the incident light, with two mirrors positioned at orthogonal arms—one fixed and one movable. The movable mirror can be actuated by a piezoelectric or electrodynamic platform, allowing for precise control of the optical path difference. The recombined light is then focused onto the detector, ensuring direct optical communication between the interferometer and the detector, and enabling the modulation of the light for spectral analysis. Alternatively, a Mach-Zehnder interferometer can be constructed using two beam splitters and two mirrors, with the output guided to the detector via relay optics. Careful alignment and coupling ensure efficient operation of the interferometer in a multispectral imager and delivers high-quality interferograms to the detector for subsequent processing.

[0054] Step 630 involves mounting a spatially variable spectral filter near the detector and interferometer. The spatially variable spectral filter is designed with multiple bandpass regions, each selectively transmitting a specific range of wavelengths. This configuration allows the filter to spatially split the incident light, such that each region of the detector receives only the spectral band assigned to that region.

[0055] Filters can be mounted in various ways, depending on the instrument configuration and desired optical performance. A common approach is to position the filter at the intermediate image plane between the interferometer and the detector. In this configuration, the filter is held in a precision filter holder or frame, which can be attached to an optical mount or integrated into the detector assembly housing. The filter holder may include alignment features such as locating pins, slots, or adjustable supports to ensure precise positioning of the filter relative to the detector pixels and optical axis. In some designs, the filter can be mounted directly onto the detector package using adhesives, mechanical clips, or custom brackets that hold the filter in place while minimizing optical loss and stray light.

[0056] Alternatively, the filter can be mounted close to the detector, such as on the surface of the detector window or within a thin gap between the detector and the final lens of the rear optical system. This approach can be useful for small instruments or when the filter needs to be easily replaceable or interchangeable. In some cases, the filter can be integrated into a filter cartridge or tube that slides into a slot near the detector, allowing for rapid filter exchange to accommodate different measurement requirements or spectral bands.

[0057] In another embodiment, the filter can be fabricated directly on the detector surface without adding additional optical or physical components to the optical system.

[0058] Spatially variable spectral filters can take many forms. For example, they can be fabricated as patterned thin-film filters on an infrared-transparent substrate, where each region is deposited using techniques such as sputtering, evaporation, or photolithography to achieve the desired bandpass characteristics. Filters can also be constructed as mosaics of discrete filter tiles, each corresponding to a different spectral band, and arranged in a grid or stripe pattern to match the detector layout. In advanced designs, filters can be microfabricated arrays of bandpass elements, such as dielectric stacks or interferometric coatings, precisely designed to provide sharp spectral transitions and high transmittance within each region.

[0059] As described above, spatially variable spectral filters can be designed to include any number of bandpass regions, each designed to transmit a specific range of wavelengths to a corresponding region of the detector. In its simplest form, the filter can have two bandpass regions, such as one region transmitting short-wave infrared and another transmitting long-wave infrared. These regions can be arranged as adjacent stripes, patches, or other patterns that match the geometry of the detector array, ensuring that each region of the detector receives light only within its designated spectral band.

[0060] In some examples, as described above, a spatially variable spectral filter is positioned at an intermediate image plane between the interferometer and the detector. The intermediate image plane is a location in the optical path where an image of the observed scene is formed by optical components before reaching the detector. By positioning the spectral filter at this plane, the system ensures that the filter can selectively transmit different spectral bands to different regions of the detector based on the spatial arrangement of the filter's bandpass regions. Placing the filter between the interferometer and the detector allows the modulated light (containing coded spectral information from the interferometer) to be separated into individual spectral bands before detection. This configuration is advantageous because it enables efficient multi-band imaging and spectral separation while maintaining the integrity of the spatial and spectral information collected by the system.

[0061] Another advantage of placing the filter between the interferometer and the detector is that light reflected from the environment around the filter (labeled stray light) and light reaching the detector are not modulated by the interferometer and are therefore automatically ignored after demodulation (Fourier transform). This means that changes in such stray light, such as those caused by temperature variations in the lenses and mechanical parts around the filter, will not affect the recorded signal, thus giving the instrument a higher degree of accuracy in radiometric measurements.

[0062] As described above, embodiments of this disclosure can be designed for use on spaceborne platforms (such as satellites or spacecraft), airborne platforms (such as aircraft, drones, or balloons), or ground platforms. Furthermore, the system is configured for remote sensing applications, meaning it is designed to collect data about the environment from a distance. Specifically, the system can be used to sense and analyze the atmosphere (e.g., measuring gases, temperature, or humidity) or the Earth's surface (e.g., mapping landforms, vegetation, or water bodies).

[0063] In summary, the disclosed multi-band imaging spectrometer system represents a significant advancement in remote sensing technology by simultaneously acquiring multiple spectral bands using a single detector and spatially varied spectral filters. By simplifying optical design and reducing hardware complexity, this invention provides a versatile and effective solution for a wide range of applications, including atmospheric monitoring, Earth observation, and environmental analysis from airborne or spaceborne platforms. The integration of advanced data processing capabilities further enhances the system's ability to provide high-resolution, multi-band spectral information, supporting more accurate and comprehensive scientific and operational insights.

[0064] Project 1. A system comprising: a detector positioned at an end of an optical path; a set of optical components positioned along the optical path such that the set of optical components directs light from a scene to the detector, the set of optical components including an interferometer configured to create a set of interferograms; a spatially variable spectral filter positioned along the optical path and configured to expose different regions of the detector to different spectral bands of light originating from the scene; and a processor communicatively coupled to the detector and configured to process the set of interferograms detected by the detector in a manner that extracts spectral information from the set of interferograms.

[0065] Project 2. The system according to Project 1, wherein the spatially varied spectral filter includes at least two bandpass regions, each bandpass region being configured to transmit different spectral bands to the corresponding region of the detector.

[0066] Project 3. Based on the systems of Projects 1 to 2, the spatially varied spectral filter is positioned at the intermediate image plane between the interferometer and the detector.

[0067] Project 4. Based on the systems of Projects 1 to 3, the spatially varied spectral filter is positioned at the intermediate image plane before the interferometer.

[0068] Project 5. Based on the systems of Projects 1 to 4, in which the spatially varied spectral filter is placed directly on the surface of the detector.

[0069] Project 6. The system according to Projects 1 to 5, wherein the group of optical components further includes a front optics device configured to guide at least a portion of the light from the scene through the interferometer.

[0070] Project 7. Based on the systems in Projects 1 to 6, the spatially varying spectral filters include short-wave infrared bandpass, mid-wave infrared bandpass, and long-wave infrared bandpass.

[0071] Project 8. The system according to Projects 1 to 7, wherein the system is configured to be coupled to at least one of a spaceborne platform or an airborne platform; and to be used for remote sensing of at least one of the atmosphere or the Earth's surface.

[0072] Project 9. The system based on Projects 1 through 8, wherein the processor is also configured to stitch together spatial and spectral information from different regions of the detector to generate a synthetic multi-band spectral image.

[0073] Project 10. A system based on Projects 1 through 9, wherein the processor is configured to process the set of interferograms by performing a Fourier transform on each of the interferograms in the set.

[0074] Project 11. A method for manufacturing a multi-band imaging spectrometer device, the method comprising: coupling a detector to a circuit configured to process an interferogram generated by the detector; assembling an interferometer in optical communication with the detector, the interferometer being configured to direct modulated light to the detector; mounting a spatially varied spectral filter near the detector and the interferometer, the filter being adapted to expose different regions of the detector to different spectral bands of the modulated light; and arranging a set of optical components, including the interferometer and the spatially varied spectral filter, such that light from the scene passes through the interferometer and the filter before reaching the detector.

[0075] Project 12. According to the method of Project 11, wherein configuring the circuit to process the interferogram includes configuring the circuit to perform a Fourier transform on each interferogram generated by the detector, thereby extracting spectral information of each region of the detector.

[0076] Project 13. According to the method of Projects 11 to 12, the method further includes configuring a spatially varied spectral filter to include at least two bandpass regions, each bandpass region being configured to transmit different spectral bands.

[0077] Project 14. According to the method of Projects 11 to 13, the arrangement of the set of optical components includes positioning a spatially varied spectral filter at an intermediate image plane between the interferometer and the detector.

[0078] Project 15. According to the method of Projects 11 to 14, the method further includes positioning the spatially varied spectral filter at an intermediate image plane before the interferometer.

[0079] Item 16. A system comprising: a spectrometer including: a detector positioned at an end of an optical path; a set of optical components positioned along the optical path such that the set of optical components directs light from a scene to the detector; the set of optical components including an interferometer configured to create a set of interferograms; a spatially varying spectral filter positioned along the optical path and configured to expose different regions of the detector to different spectral bands of light originating from the scene; a processor communicatively coupled to the detector and configured to process the set of interferograms detected by the detector in a manner that extracts spectral information from the set of interferograms; and a mounting interface configured to attach the spectrometer to a remote sensing platform.

[0080] Project 17. The system based on Project 16, wherein the remote sensing platform includes a spaceborne platform.

[0081] Project 18. The system based on Projects 16 to 17, in which a spectrometer is configured for remote sensing of the Earth's atmosphere.

[0082] Project 19. Systems based on Projects 16 to 18, wherein the remote sensing platform includes an airborne platform.

[0083] Project 20. A system based on Projects 16 to 19, in which a spectrometer is configured for remote sensing of the Earth's surface.

[0084] While the foregoing disclosure illustrates various embodiments using specific block diagrams, flowcharts, and examples, the various block diagram components, flowchart steps, operations, and / or components described and / or illustrated herein can be implemented individually and / or jointly using various hardware, software, or firmware (or any combination thereof) configurations. Furthermore, any disclosure of components contained within other components should be considered exemplary in nature, as many other architectures can be implemented to achieve the same functionality.

[0085] The process parameters and sequence of steps described and / or illustrated herein are given by way of example only and may be changed as needed. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order shown or discussed. The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein, or include additional steps in addition to those disclosed.

[0086] The foregoing description is intended to enable others skilled in the art to best utilize the various aspects of the exemplary embodiments disclosed herein. This exemplary description is not intended to be exhaustive or limited to any precise forms disclosed. Many modifications and variations are possible without departing from the spirit and scope of this disclosure. The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. In determining the scope of this disclosure, reference should be made to the appended claims and their equivalents.

[0087] Unless otherwise stated, the terms “connected to” and “coupled to” (and their derivatives) used in the specification and claims should be understood to allow for direct and indirect (i.e., via other elements or components) connections. Furthermore, the terms “a” or “an” used in the specification and claims should be understood to mean “at least one of”. Finally, for ease of use, the terms “including” and “having” (and their derivatives) used in the specification and claims are interchangeable with the word “comprising” and have the same meaning.

Claims

1. A system comprising: A detector, which is positioned at the end of the optical path; A set of optical components, positioned along the optical path such that the set of optical components guides light from the scene to the detector, the set of optical components including an interferometer configured to create a set of interferograms; A spatially variable spectral filter, which is positioned along the optical path and configured to expose different regions of the detector to different spectral bands of the light originating from the scene; as well as A processor is communicatively coupled to the detector and configured to process the set of interferograms detected by the detector in a manner that extracts spectral information from the set of interferograms.

2. The system of claim 1, wherein the spatially varied spectral filter comprises at least two bandpass regions, each bandpass region being configured to transmit different spectral bands to a corresponding region of the detector.

3. The system of claim 1, wherein the spatially varying spectral filter is positioned at an intermediate image plane between the interferometer and the detector.

4. The system of claim 1, wherein the spatially varied spectral filter is positioned at an intermediate image plane prior to the interferometer.

5. The system of claim 1, wherein the spatially varied spectral filter is positioned on the surface of the detector.

6. The system of claim 1, wherein the set of optical components further includes a front optics device configured to guide at least a portion of the light from the scene through the interferometer.

7. The system according to claim 1, wherein the spatially varying spectral filter includes a short-wave infrared bandpass region, a mid-wave infrared bandpass region, and a long-wave infrared bandpass region.

8. The system of claim 1, wherein the system is configured to: Coupled to at least one of a spaceborne platform or an airborne platform; and Used for remote sensing of at least one of the atmosphere or the Earth's surface.

9. The system of claim 8, wherein the processor is further configured to stitch together spatial and spectral information from the different regions of the detector to generate a composite multiband spectral image.

10. The system of claim 8, wherein the processor is configured to process the set of interferograms by performing a Fourier transform on each of the interferograms.

11. A method for manufacturing a multi-band imaging spectrometer, the method comprising: The detector is coupled to a circuit, which is configured to process the interferogram generated by the detector. An interferometer is assembled to optically communicate with the detector, the interferometer being configured to direct modulated light to the detector; A spatially variable spectral filter is installed near the detector and the interferometer, the filter being adapted to expose different regions of the detector to different spectral bands of the modulated light; as well as A set of optical components is arranged such that light from the scene passes through the interferometer and the filter before reaching the detector.

12. The method of claim 11, wherein configuring the circuit to process the interferograms includes configuring the circuit to perform a Fourier transform on each interferogram generated by the detector, thereby extracting spectral information of each region of the detector.

13. The method of claim 11, further comprising configuring the spatially varied spectral filter to include at least two bandpass regions, each bandpass region being configured to transmit different spectral bands.

14. The method of claim 11, wherein arranging the set of optical components includes positioning the spatially varied spectral filter at an intermediate image plane between the interferometer and the detector.

15. The method of claim 11, further comprising positioning the spatially varied spectral filter at an intermediate image plane preceding the interferometer.

16. A system comprising: Spectrometer, including: A detector, which is positioned at the end of the optical path. A set of optical components, positioned along the optical path such that they guide light from the scene to the detector, includes an interferometer configured to create a set of interferograms. A spatially variable spectral filter, positioned along the optical path and configured to expose different regions of the detector to different spectral bands of the light originating from the scene, and A processor communicatively coupled to the detector and configured to process the set of interferograms detected by the detector in a manner that extracts spectral information from the set of interferograms; and An installation interface is configured to attach the spectrometer to a remote sensing platform.

17. The system of claim 16, wherein the remote sensing platform includes a spaceborne platform.

18. The system of claim 17, wherein the spectrometer is configured for remote sensing of the Earth's atmosphere.

19. The system of claim 16, wherein the remote sensing platform includes an airborne platform.

20. The system of claim 19, wherein the spectrometer is configured for remote sensing of the Earth's surface.

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