TECHNICAL FIELD

The present invention generally relates to a system and method for gas cloud detection and, in particular, to a system and method of detecting spectral signatures of chemical compositions in a mid- and long-wave infrared spectral region.

DESCRIPTION OF THE RELATED TECHNOLOGY

Spectral imaging systems and methods have applications in a variety of fields. Spectral imaging systems and methods obtain a spectral image of a scene in one or more regions of the electromagnetic spectrum to detect phenomena, identify material compositions or characterize processes. The spectral image of the scene can be represented as a three-dimensional data cube where two axes of the cube represent two spatial dimensions of the scene and a third axes of the data cube represents spectral information of the scene in different wavelength regions. The data cube can be processed using mathematical methods to obtain information about the scene. Some of the existing spectral imaging systems generate the data cube by scanning the scene in the spatial domain (e.g., by moving a slit across the horizontal dimensions of the scene) and/or spectral domain (e.g., by scanning a wavelength dispersive element to obtain images of the scene in different spectral regions). Such scanning approaches acquire only a portion of the full data cube at a time. These portions of the full data cube are stored and then later processed to generate a full data cube.

SUMMARY

The systems, methods and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

Various embodiments of the systems described herein provide an infrared (IR) imaging system for determining a concentration of a target chemical species in an object (e.g., a gas plume). The imaging system includes (i) an optical system, having an optical focal plane array (FPA) unit configured to receive IR radiation from the object along at least two or more optical channels defined by components of the optical system, the at least two or more optical channels being spatially and spectrally different from one another; and (ii) a processor or processing electronics configured to acquire multispectral optical data representing said target chemical species from the received IR radiation in a single occurrence of data acquisition (or snapshot). The optical FPA unit includes an array of photo-sensitive devices that are disposed at the focus of one or more lenses. In various embodiments, the array of photo-sensitive devices can include a two-dimensional imaging sensor that is sensitive to radiation having wavelengths between 1 μm and 20 μm (for example, in mid infra-red wavelength range, long infra-red wavelength range, visible wavelength range, etc.). In various embodiments, the array of photo-sensitive devices can include CCD or CMOS sensors, bolometers or other detectors that are sensitive to infra-red radiation. The optical system may include an optical aperture (a boundary of which is defined to circumscribe or encompass the at least two or more spatially distinct optical channels) and one or more optical filters. In various implementations, the one or more optical filters can comprise at least two spectrally-multiplexed filters. Each of these optical filters can be associated with one of the at least two or more optical channels and configured to transmit a portion of the IR radiation received in the associated optical channel. In various embodiments, the one or more optical filters can be spectrally multiplexed and may include, for example, at least one of a longpass optical filter and a shortpass optical filter, or a band pass filter (with or without a combination with another filter such as a notch filter, for example). The optical system may further include at least two reimaging lenses. The at least two reimaging lenses, for example each of the reimaging lens, may be disposed to transmit IR radiation (for example, between about 1 micron and about 20 microns), that has been transmitted through a corresponding optical filter towards the optical FPA unit. In one embodiment, the optical FPA unit is positioned to receive IR radiation from the object through the at least two reimaging lenses to form respectively-corresponding two or more sets of imaging data representing the object. The processor or processing electronics is configured to acquire this optical data from the two or more sets of imaging data. In various embodiments of the imaging systems, the FPA unit may be devoid of cooling systems. In various embodiments, two or more of the array of photo-sensitive devices may be uncooled. In some embodiments, the system further comprises two or more temperature-controlled shutters removably positioned to block IR radiation incident onto the optical system from the object.

Also disclosed herein is an implementation of a method of operating an infrared (IR) imaging system. The method includes receiving IR radiation from an object through at least two optical channels defined by components of an optical system of the IR imaging system, which at least two optical channels are spatially and spectrally different from one another. The method further includes transmitting the received IR radiation towards an optical focal plane array (FPA) unit that is not being cooled in the course of normal operation. For example, in various embodiments of the imaging systems, the FPA unit may be devoid of cooling systems. In various embodiments, two or more of the array of photo-sensitive devices may be uncooled. Some embodiments further comprise removably positioning at least one of at least two temperature-controlled shutters in front of the optical system to block IR radiation incident onto the optical system from the object.

Various innovative aspects of the subject matter described in this disclosure can be implemented in the following embodiments:

Embodiment 1: An infrared (IR) imaging system, the imaging system comprising:a plurality of cameras;at least one thermal reference source having a known temperature placed in front of the plurality of cameras and configured to be imaged by the plurality of cameras; anda data-processing unit comprising a processor, the imaging system configured to:acquire with the plurality of cameras a plurality of frames having regions that correspond to the image of the reference source; andapply a dynamic calibration correction to the plurality of cameras to allow every camera in the plurality of cameras to be calibrated to agree with every other camera in the plurality imaging the reference source.

Embodiment 2: The system of Embodiment 1, wherein the plurality of cameras comprises a FPA unit and a plurality of lenses.

Embodiment 3: The system of any of Embodiments 1-2, wherein the FPA unit comprises one FPA or a plurality of FPAs.

Embodiment 4: The system of any of Embodiments 1-3, wherein the at least one thermal reference source has a known spectrum.

Embodiment 5: The system of any of Embodiments 1-4, further comprising an additional thermal reference source imaged by the plurality of cameras.

Embodiment 6: The system of any of Embodiments 1-5, wherein the additional reference source has a temperature and a spectrum different from the known temperature and the known spectrum of the at least one reference source.

Embodiment 7: The system of any of Embodiments 1-6, wherein the temperature of the additional thermal reference source is less than the known temperature.

Embodiment 8: The system of any of Embodiments 1-7, wherein the temperature of the additional thermal reference source is greater than the known temperature.

Embodiment 9: The system of any of Embodiments 1-8, wherein the at least one reference source is displaced away from a conjugate image plane of the plurality of cameras such that the image of the at least one reference source captured by the plurality of cameras is blurred.

Embodiment 10: The system of any of Embodiments 1-9, wherein the at least one reference source is positioned at a conjugate image plane of the plurality of cameras.

Embodiment 11: The system of any of Embodiments 1-10, further comprising a plurality of mirrors configured to image the at least one reference source onto the plurality of cameras.

Embodiment 12: The system of any of Embodiments 1-11, wherein the plurality of mirrors are disposed outside a central field of view of the plurality of cameras.

Embodiment 13: The system of any of Embodiments 1-12, further comprising a first and a second temperature-controlled shutter removably positioned to block IR radiation incident on the system from reaching the plurality of cameras.

Embodiment 14: The system of any of Embodiments 1-13, wherein the system includes at least two spatially and spectrally different optical channels.

Embodiment 15: The system of any of Embodiments 1-14, wherein the system includes at least three optical channels.

Embodiment 16: The system of any of Embodiments 1-15, wherein the system includes at least four optical channels.

Embodiment 17: The system of any of Embodiments 1-16, wherein the system includes at least five optical channels.

Embodiment 18: The system of any of Embodiments 1-17, wherein the system includes at least six optical channels.

Embodiment 19: The system of any of Embodiments 1-18, wherein the system includes at least seven optical channels.

Embodiment 20: The system of any of Embodiments 1-19, wherein the system includes at least eight optical channels.

Embodiment 21: The system of any of Embodiments 1-20, wherein the system includes at least nine optical channels.

Embodiment 22: The system of any of Embodiments 1-21, wherein the system includes at least ten optical channels.

Embodiment 23: The system of any of Embodiments 1-22, wherein the system includes at least twelve optical channels.

Embodiment 24: The system of any of Embodiments 1-23, further comprising one or more sensors configured to measure a temperature of the at least one reference source.

Embodiment 25: The system of any of Embodiments 1-24, wherein the plurality of cameras is configured to image the same portion of the at least one reference source.

Embodiment 26: An infrared (IR) imaging system, the imaging system comprising:a plurality of cameras;a first temperature-controlled reference source imaged by the plurality of cameras;a second temperature-controlled reference source imaged by the plurality of cameras; anda data-processing unit comprising a processor, said data-processing unit configured to:acquire with the plurality of cameras a plurality of frames having regions that correspond to the image of the reference source; anddynamically calibrate the plurality of cameras so that various cameras imaging a scene are forced to agree on a temperature estimate of the first and second reference sources.

Embodiment 27: The imaging system of any of Embodiment 26, wherein the data-processing unit is configured to calculate a dynamic calibration correction and apply the correction to the plurality of cameras for each of the plurality of frames.

Embodiment 28: The system of any of Embodiments 26-27, wherein the first reference source is maintained at a first temperature.

Embodiment 29: The system of any of Embodiments 26-28, wherein the second reference source is maintained at a second temperature.

Embodiment 30: The system of any of Embodiments 26-29, wherein the first temperature is greater than the second temperature.

Embodiment 31: The system of any of Embodiments 26-30, wherein the first temperature is less than the second temperature.

Embodiment 32: The system of any of Embodiments 26-31, wherein the first and the second reference sources are displaced away from a conjugate image plane of the plurality of cameras such that the image of the first and the second reference sources captured by the plurality of cameras is blurred.

Embodiment 33: The system of any of Embodiments 26-32, wherein the first and the second reference sources are positioned at a conjugate image plane of the plurality of cameras.

Embodiment 34: The system of any of Embodiments 26-33, further comprising:a first mirror configured to image the first reference onto the plurality of cameras; anda second mirror configured to image the second reference source onto the plurality of cameras.

Embodiment 35: The system of any of Embodiments 26-34, further comprising a first and a second temperature-controlled shutter removably positioned to block IR radiation incident on the system from reaching the plurality of cameras.

Embodiment 36: The system of any of Embodiments 26-35, wherein the system includes at least two spatially and spectrally different optical channels.

Embodiment 37: The system of any of Embodiments 26-36, wherein the system includes at least four optical channels.

Embodiment 38: The system of any of Embodiments 26-37, wherein the system includes at least six optical channels.

Embodiment 39: The system of any of Embodiments 26-38, wherein the system includes at least eight optical channels.

Embodiment 40: The system of any of Embodiments 26-39, wherein the system includes at least ten optical channels.

Embodiment 41: The system of any of Embodiments 26-40, wherein the system includes at least twelve optical channels.

Embodiment 42: The system of any of Embodiments 26-41, further comprising one or more sensors configured to measure a temperature of the first or the second reference source.

Embodiment 43: The system of any of Embodiments 26-42, wherein the plurality of cameras is configured to image the same portion of the first reference source and wherein plurality of cameras is configured to image the same portion of the second reference source.

Embodiment 44: An infrared (IR) imaging system, the imaging system comprising:a plurality of cameras;a reference having an unknown temperature configured to be imaged by the plurality of cameras; anda data-processing unit comprising a processor, the imaging system configured to:acquire with the plurality of cameras a plurality of frames having regions that correspond to the image of the reference;calculate a dynamic calibration correction using a temperature measured by one of the cameras in the plurality of cameras as a reference temperature; andapply the calibration correction to the other cameras in the plurality of cameras to match the temperature estimate of the other cameras in the plurality of cameras with the reference temperature.

Embodiment 45: The system of any of Embodiment 44, wherein the reference is displaced away from a conjugate image plane of the plurality of cameras such that the image of the reference source captured by the plurality of cameras is blurred.

Embodiment 46: The system of any of Embodiments 44-45, wherein the reference is positioned at a conjugate image plane of the plurality of cameras.

Embodiment 47: The system of any of Embodiments 44-46, further comprising a plurality of mirrors configured to image the reference onto the plurality of cameras.

Embodiment 48: The system of any of Embodiments 44-47, further comprising a first and a second temperature-controlled shutter removably positioned to block IR radiation incident on the system from reaching the plurality of cameras.

Embodiment 49: The system of any of Embodiments 44-48, wherein the system includes at least two spatially and spectrally different optical channels.

Embodiment 50: The system of any of Embodiments 44-49, wherein the system includes at least three optical channels.

Embodiment 51: The system of any of Embodiments 44-50, wherein the system includes at least four optical channels.

Embodiment 52: The system of any of Embodiments 44-51, wherein the system includes at least five optical channels.

Embodiment 53: The system of any of Embodiments 44-52, wherein the system includes at least six optical channels.

Embodiment 54: The system of any of Embodiments 44-52, wherein the system includes at least seven optical channels.

Embodiment 55: The system of any of Embodiments 44-53, wherein the system includes at least eight optical channels.

Embodiment 56: The system of any of Embodiments 44-54, wherein the system includes at least nine optical channels.

Embodiment 57: The system of any of Embodiments 44-55, wherein the system includes at least ten optical channels.

Embodiment 58: The system of any of Embodiments 44-56, wherein the system includes at least twelve optical channels.

Embodiment 59: The system of any of Embodiments 44-57, wherein the plurality of cameras is configured to image the same portion of the reference.

Embodiment 60: An infrared (IR) imaging system, the imaging system comprising:an optical system including an optical focal plane array (FPA) unit, the optical system includes components associated with at least two optical channels, said at least two optical channels being spatially and spectrally different from one another, each of the at least two optical channels positioned to transfer IR radiation incident on the optical system towards the optical FPA unit, the optical FPA unit comprising at least two detector arrays disposed at a distance from two corresponding focusing lenses;at least one thermal reference having a known temperature, wherein radiation emitted from the at least one reference is directed towards the optical FPA unit and imaged by the at least two detector arrays; anda data-processing unit, said data-processing unit configured to:acquire a plurality of frames with the at least two detector arrays having regions in the plurality of image frames that correspond to the image of the reference; anddynamically calibrate the at least two detector arrays to address a difference in the temperature estimate of the reference between the two detector arrays.

Embodiment 61: The system of any of Embodiment 60, wherein the at least one thermal reference has a known spectrum.

Embodiment 62: The system of any of Embodiments 60-61, further comprising an additional thermal reference, wherein radiation from the additional reference is directed towards the optical FPA unit and imaged by the at least two detector arrays.

Embodiment 63: The system of any of Embodiments 60-62, wherein the additional reference has a temperature and a spectrum different from the known temperature and the known spectrum of the at least one reference source.

Embodiment 64: The system of any of Embodiments 60-63, wherein the temperature of the additional thermal reference is less than the known temperature.

Embodiment 65: The system of any of Embodiments 60-64, wherein the temperature of the additional thermal reference is greater than the known temperature.

Embodiment 66: The system of any of Embodiments 60-65, wherein the at least one reference is displaced away from a conjugate image plane of the at least two detector arrays such that the image of the at least one reference captured by the at least two detector arrays is defocused.

Embodiment 67: The system of any of Embodiments 60-66, wherein the at least one reference is positioned at a conjugate image plane of the at least two detector arrays such that the image of the at least one reference captured by the at least two detector arrays is focused.

Embodiment 68: The system of any of Embodiments 60-67, further comprising at least two reflecting elements configured to direct radiation from the at least one reference source toward the at least two detector arrays.

Embodiment 69: The system of any of Embodiments 60-68, wherein the at least two reflecting elements are disposed outside a central field of view of the at least two detector arrays.

Embodiment 70: The system of any of Embodiments 60-69, further comprising a third detector array disposed between the at least two detector arrays.

Embodiment 71: The system of any of Embodiments 60-70, wherein the data-processing unit is configured to:acquire a plurality of frames using the third detector array; anddynamically calibrate the third detector array to match a temperature estimate of the third detector array with the temperature estimates of the at least two detector arrays.

Embodiment 72: The system of any of Embodiments 60-71, wherein radiation emitted from the at least one reference source is not imaged by the third detector array.

Embodiment 73: The system of any of Embodiments 60-72, wherein the third detector array has a field of view greater than a field of view of the at least two detector arrays.

Embodiment 74: The system of any of Embodiments 60-73, wherein the at least one reference is imaged by the third detector array.

Embodiment 75: The system of any of Embodiments 60-74, further comprising a third reflecting element disposed outside the field of view of the at least two detector arrays and configured to image the at least one reference onto the third detector array.

Embodiment 76: The system of any of Embodiments 60-75, further comprising a first and a second temperature-controlled element removably positioned to block IR radiation incident on the optical system from reaching the optical FPA unit.

Embodiment 77: The system of any of Embodiments 60-76, wherein the optical system includes components associated with three optical channels.

Embodiment 78: The system of any of Embodiments 60-77 wherein the optical system includes components associated with four optical channels.

Embodiment 79: The system of any of Embodiments 60-78, wherein the optical system includes components associated with six optical channels.

Embodiment 80: The system of any of Embodiments 60-79, wherein the optical system includes components associated with eight optical channels.

Embodiment 81: The system of any of Embodiments 60-80, wherein the optical system includes components associated with ten optical channels.

Embodiment 82: The system of any of Embodiments 60-81, wherein the optical system includes components associated with twelve optical channels.

Embodiment 83: The system of any of Embodiments 60-82, wherein the optical system includes components associated with sixteen optical channels.

Embodiment 84: The system of any of Embodiments 60-83, wherein the optical system includes components associated with twenty four optical channels.

Embodiment 85: The system of any of Embodiments 60-84, wherein each of the at least two detector arrays is configured to image the same portion of the at least one reference so as to consistently provide a common reference temperature.

Embodiment 86: The system of any of Embodiments 60-85, wherein the data-processing unit comprises processing electronics.

Embodiment 87: The system of any of Embodiments 60-86, wherein the data-processing unit comprises a processor.

Embodiment 88: The system of any of Embodiments 60-87, wherein the data-processing unit comprises one or more processors.

Embodiment 89: An infrared (IR) imaging system, the imaging system comprising:an optical system including an optical focal plane array (FPA) unit, the optical system including at least two optical channels, said at least two optical channels being spatially and spectrally different from one another, each of the at least two optical channels positioned to transfer IR radiation incident on the optical system towards the optical FPA unit, the optical FPA unit comprising at least two detector arrays disposed at a distance from two corresponding focusing lenses;a first temperature-controlled reference imaged by the at least two detector arrays;a second temperature-controlled reference imaged by the at least two detector arrays; anda data-processing unit configured to:acquire a plurality of frames with the at least two detector arrays having regions in the plurality of image frames that correspond to the image of the first and second references; anddynamically calibrate the at least two detector arrays to address a difference in a temperature estimate of the first and second references between the two detector arrays.

Embodiment 90: The system of Embodiment 89, wherein the first reference is maintained at a first temperature.

Embodiment 91: The system of any of Embodiments 89-90, wherein the second reference is maintained at a second temperature.

Embodiment 92: The system of any of Embodiments 89-91, wherein the first temperature is greater than the second temperature.

Embodiment 93: The system of any of Embodiments 89-92, wherein the first temperature is less than the second temperature.

Embodiment 94: The system of any of Embodiments 89-93, wherein the first and the second references are displaced away from a conjugate image plane of the at least two detector arrays such that the image of the first and the second references captured by the at least two detector arrays is defocused.

Embodiment 95: The system of any of Embodiments 89-94, wherein the first and the second references are positioned at a conjugate image plane of the at least two detector arrays such that the image of the first and the second references captured by the at least two detector arrays is focused.

Embodiment 96: The system of any of Embodiments 89-95, further comprising:a first reflecting element configured to direct radiation from the first reference toward the at least two detector arrays; anda second reflecting element configured to direct radiation from the second reference toward the at least two detector arrays.

Embodiment 97: The system of any of Embodiments 89-96, wherein the first reflecting element is disposed outside a field of view of the at least two detector arrays.

Embodiment 98: The system of any of Embodiments 89-97, wherein the second reflecting element is disposed outside a field of view of the at least two detector arrays.

Embodiment 99: The system of any of Embodiments 89-98, further comprising a third detector array disposed between the at least two detector arrays.

Embodiment 100: The system of any of Embodiments 89-99, wherein the data-processing unit is configured to:acquire a plurality of frames using the third detector array; anddynamically calibrate the third detector array to address a difference in the temperature estimate of the first and second references between the third detector array and the two detector arrays.

Embodiment 101: The system of any of Embodiments 89-100, wherein the first and second references are not imaged by the third detector array.

Embodiment 102: The system of any of Embodiments 89-101, wherein the third detector array has a field of view greater than a field of view of the at least two detector arrays.

Embodiment 103: The system of any of Embodiments 89-102, wherein r first and second references are imaged by the third detector array.

Embodiment 104: The system of any of Embodiments 89-103, further comprising a third reflecting element disposed outside the field of view of the at least two detector arrays and configured to image the first and second references onto the third detector array.

Embodiment 105: The system of any of Embodiments 89-104, further comprising a first and a second temperature-controlled element removably positioned to block IR radiation incident on the optical system from reaching the optical FPA unit.

Embodiment 106: The system of any of Embodiments 89-105, wherein the optical system includes components associated with three optical channels.

Embodiment 107: The system of any of Embodiments 89-106, wherein the optical system includes components associated with four optical channels.

Embodiment 108: The system of any of Embodiments 89-107, wherein the optical system includes components associated with five optical channels.

Embodiment 109: The system of any of Embodiments 89-108, wherein the optical system includes components associated with six optical channels.

Embodiment 110: The system of any of Embodiments 89-109, wherein the optical system includes components associated with seven optical channels.

Embodiment 111: The system of any of Embodiments 89-110, wherein the optical system includes components associated with eight optical channels.

Embodiment 112: The system of any of Embodiments 89-111, wherein the optical system includes components associated with ten optical channels.

Embodiment 113: The system of any of Embodiments 89-112, wherein the optical system includes components associated with twelve optical channels.

Embodiment 114: The system of any of Embodiments 89-113, wherein each of the at least two detector arrays is configured to image the same portion of the first reference source so as to consistently provide a common first reference temperature and wherein each of the at least two detector arrays is configured to image the same portion of the second reference source so as to consistently provide a common second reference temperature.

Embodiment 115: The system of any of Embodiments 89-114, further comprising a temperature controller configured to control the temperature of the first or second reference.

Embodiment 116: The system of any of Embodiments 89-115, further comprising one or more sensors configured to measure a temperature of the first or the second reference.

Embodiment 117: The system of any of Embodiments 89-116, wherein the one or more sensors are configured to communicate the measured temperature of the first or the second reference to a temperature controller.

Embodiment 118: The system of any of Embodiments 89-117, wherein the one or more sensors are configured to communicate the measured temperature of the first or the second reference to the data-processing unit.

Embodiment 119: The system of any of Embodiments 89-118, wherein the first or the second reference is associated with a heater.

Embodiment 120: The system of any of Embodiments 89-119, wherein the first or the second reference is associated with a cooler.

Embodiment 121: The system of any of Embodiments 89-120, wherein the data-processing unit comprises processing electronics.

Embodiment 122: The system of any of Embodiments 89-121, wherein the data-processing unit comprises a processor.

Embodiment 123: The system of any of Embodiments 89-122, wherein the data-processing unit comprises one or more processors.

Embodiment 124: An infrared (IR) imaging system, the imaging system comprising:an optical system including components associated with at least two optical channels, said at least two optical channels being spectrally different from one another, each of the at least two optical channels positioned to transfer IR radiation incident on the optical system towards a plurality of cameras;at least one calibration surface with unknown temperature and imaged by each of the at least two detectors; anda data-processing unit configured to:acquire a plurality of image frames with the plurality of cameras including the imaged surface; andadjust one or more parameters of the cameras in the plurality of cameras such that a temperature estimate of the calibration surface of the cameras in the plurality of cameras agree with each other.

Embodiment 125: The system of Embodiment 124, wherein the one or more parameters is associated with a gain of the cameras in the plurality of cameras.

Embodiment 126: The system of any of Embodiments 124-125, wherein the one or more parameters is associated with a gain offset of the cameras in the plurality of cameras.

Embodiment 127: The system of any of Embodiments 124-126, wherein the calibration surface is displaced away from a conjugate image plane of the plurality of cameras such that an image of the surface is defocused.

Embodiment 128: The system of any of Embodiments 124-127, wherein the calibration surface is positioned at a conjugate image plane of the plurality of cameras such that an image of the surface is focused.

Embodiment 129: The system of any of Embodiments 124-128, further comprising at least one reflecting element configured to image the surface onto the plurality of cameras.

Embodiment 130: The system of any of Embodiments 124-129, further comprising a first and a second temperature-controlled element removably positioned to block IR radiation incident on the optical system from reaching the plurality of cameras.

Embodiment 131: The system of any of Embodiments 124-130, wherein the optical system includes components associated with three optical channels.

Embodiment 132: The system of any of Embodiments 124-131, wherein the optical system includes components associated with four optical channels.

Embodiment 133: The system of any of Embodiments 124-132, wherein the optical system includes components associated with six optical channels.

Embodiment 134: The system of any of Embodiments 124-133, wherein the optical system includes components associated with eight optical channels.

Embodiment 135: The system of any of Embodiments 124-134, wherein the optical system includes components associated with ten optical channels.

Embodiment 136: The system of any of Embodiments 124-135, wherein the optical system includes components associated with twelve optical channels.

Embodiment 137: The system of any of Embodiments 124-136, wherein the data-processing unit comprises processing electronics.

Embodiment 138: The system of any of Embodiments 124-137, wherein the data-processing unit comprises a processor.

Embodiment 139: The system of any of Embodiments 124-138, wherein the data-processing unit comprises one or more processors.

Embodiment 140: The system of any of Embodiments 124-139, wherein the calibration surface comprises a sidewall of a housing of the system.

Embodiment 141: An infrared (IR) imaging system, the imaging system comprising:at least four spatially and spectrally different optical channels configured to receive IR radiation from a common object, each of the at least four spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the at least four different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object.

Embodiment 142: The system of Embodiment 141, further comprising twelve optical channels.

Embodiment 143: The system of any of Embodiments 141-142, configured to simultaneously acquire multispectral optical data from the at least four different optical channels.

Embodiment 144: The system of any of Embodiments 141-143, further comprising a plurality of optical filters associated with the optical channels.

Embodiment 145: The system of any of Embodiments 141-144, wherein a number of optical filters is two.

Embodiment 146: The system of any of Embodiments 141-145, wherein a number of optical filters is three.

Embodiment 147: The system of any of Embodiments 141-146, wherein a number of optical filters is four.

Embodiment 148: The system of any of Embodiments 141-147, wherein the plurality of optical filters comprise at least one long pass (LP) filter.

Embodiment 149: The system of any of Embodiments 141-148, wherein the plurality of optical filters comprise multiple long pass (LP) filters.

Embodiment 150: The system of any of Embodiments 141-149, wherein the plurality of optical filters comprise at least one short pass (SP) filter.

Embodiment 151: The system of any of Embodiments 141-150, wherein the plurality of optical filters comprise multiple short pass (SP) filters.

Embodiment 152: The system of any of Embodiments 141-151, wherein the plurality of optical filters comprise at least one band pass (BP) filter.

Embodiment 153: The system of any of Embodiments 141-152, wherein the plurality of optical filters comprise at one short pass (SP) filter and one long pass (LP) filter.

Embodiment 154: The system of any of Embodiments 141-153, wherein the FPA unit comprises a plurality of FPAs.

Embodiment 155: The system of any of Embodiments 141-154, further comprising first and second temperature-controlled elements removably positioned to block IR radiation incident on the imaging system from reaching the FPA unit.

Embodiment 156: The system of any of Embodiments 141-155, further comprising a field reference configured for dynamically calibrating a plurality of the FPAs in the FPA unit.

Embodiment 157: The system of any of Embodiments 141-156, wherein the field reference is configured to obscure a peripheral region of an image generated by a plurality of the FPAs in the FPA unit.

Embodiment 158: The system of any of Embodiments 141-157, configured to compare spectral data in at least one of the four optical channels acquired at a first instant of time with spectral data in the at least one of the four optical channels acquired at a second instant of time to generate a temporal difference image.

Embodiment 159: The system of any of Embodiments 141-158, configured to use a difference between the multispectral optical data acquired by the two optical channels to correct parallax-induced imaging errors.

Embodiment 160: The system of any of Embodiments 141-159, configured to use a difference between the multispectral optical data acquired by the two optical channels to estimate a distance between the system and the object.

Embodiment 161: The system of any of Embodiments 141-160, configured to estimate a size of the object based on the estimated distance and an optical magnification factor of the two optical channels.

Embodiment 162: The system of any of Embodiments 141-161, configured to compare spectral data in one of the at least four optical channels with spectral data in another one of the at least four optical channels to generate a spectral difference image.

Embodiment 163: The system of any of Embodiments 141-162, further comprising a visible light imaging sensor.

Embodiment 164: The system of any of Embodiments 141-163, configured to use the visible light imaging sensor to compensate for motion-induced imaging errors.

Embodiment 165: The system of any of Embodiments 141-164, configured to process the multispectral optical data by cross-correlating multispectral optical data from at least one of the optical channels with a reference spectrum.

Embodiment 166: The system of any of Embodiments 141-165, configured to process the multispectral optical data using spectral unmixing.

Embodiment 167: The system of any of Embodiments 141-166, further comprising five optical channels.

Embodiment 168: The system of any of Embodiments 141-167, further comprising six optical channels.

Embodiment 169: The system of any of Embodiments 141-168, further comprising seven optical channels.

Embodiment 170: The system of any of Embodiments 141-169, further comprising eight optical channels.

Embodiment 171: The system of any of Embodiments 141-170, further comprising nine optical channels.

Embodiment 172: The system of any of Embodiments 141-171, further comprising ten optical channels.

Embodiment 173: The system of any of Embodiments 141-172, further comprising eleven optical channels.

Embodiment 174: The system of any of Embodiments 141-173, wherein a number of optical filters is five.

Embodiment 175: The system of any of Embodiments 141-174, wherein a number of optical filters is six.

Embodiment 176: The system of any of Embodiments 141-175, wherein a number of optical filters is seven.

Embodiment 177: The system of any of Embodiments 141-176, wherein a number of optical filters is eight.

Embodiment 178: The system of any of Embodiments 141-177, wherein a number of optical filters is nine.

Embodiment 179: The system of any of Embodiments 141-178, wherein a number of optical filters is ten.

Embodiment 180: The system of any of Embodiments 141-179, wherein a number of optical filters is eleven.

Embodiment 181: The system of any of Embodiments 141-180, wherein a number of optical filters is twelve.

Embodiment 182: The system of any of Embodiments 141-181, wherein the processing electronics comprises one or more processors.

Embodiment 183: The system of any of Embodiments 141-182, further comprising a thermal reference configured to be imaged onto the FPA unit such that a plurality of frames of the acquired multispectral optical data has an image of the thermal reference source.

Embodiment 184: The system of any of Embodiments 141-183, wherein the thermal reference has a known temperature.

Embodiment 185: The system of any of Embodiments 141-184, wherein the thermal reference is a temperature-controlled reference source.

Embodiment 186: The system of any of Embodiments 141-185, wherein the temperature-controlled reference source includes a heater.

Embodiment 187: The system of any of Embodiments 141-186, wherein the temperature-controlled reference source includes a cooler.

Embodiment 188: The system of any of Embodiments 141-187, further comprising a mirror configured to image the thermal reference onto the FPA unit.

Embodiment 189: The system of any of Embodiments 141-188, wherein a temperature of the thermal reference is unknown.

Embodiment 190: The system of any of Embodiments 141-189, wherein the thermal reference is a surface.

Embodiment 191: The system of any of Embodiments 141-190, wherein the surface comprises a wall of a housing of the system.

Embodiment 192: The system of any of Embodiments 141-191, wherein different optical channels receive IR radiation from the same portion of the thermal reference so as to consistently provide a common reference temperature.

Embodiment 193: The system of any of Embodiments 141-192, wherein a temperature of the same portion of the thermal reference is unknown.

Embodiment 194: The system of any of Embodiments 141-193, configured to acquire the multispectral optical data at a frame rate between about 5 Hz to about 200 Hz.

Embodiment 195: The system of any of Embodiments 141-194, wherein one or more of the at least four optical channels is configured to collect IR radiation to provide spectral data corresponding to a discrete spectral band located in the wavelength range between about 7.9 μm and about 8.4 μm.

Embodiment 196: The system of any of Embodiments 141-195, wherein each optical channel is configured to transfer spectrally distinct, two-dimensional image data of the common object to one or more imaging sensors.

Embodiment 196: The system of any of Embodiments 1-24, wherein the one or more sensors are configured to communicate the measured temperature of the at least one reference source to a temperature controller.

Embodiment 197: The system of any of Embodiments 1-24, wherein the one or more sensors are configured to communicate the measured temperature of the at least one reference source to the data-processing unit.

Embodiment 198: The system of any of Embodiments 26-42, wherein the one or more sensors are configured to communicate measured temperature of the first or the second reference to a temperature controller.

Embodiment 199: The system of any of Embodiments 26-42, wherein the one or more sensors are configured communicate the measured temperature of the first or the second reference to the data-processing unit.

Embodiment 200: An infrared (IR) imaging system for imaging a target species in an object, the imaging system comprising:an optical system comprising an optical focal plane array (FPA) unit and defining a plurality of spatially and spectrally different optical channels to transfer IR radiation towards the optical FPA unit, each optical channel positioned to transfer a portion of the IR radiation incident on the optical system from the object towards the optical FPA unit; anda programmable processor configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium, to acquire, in a single occurrence of data acquisition, multispectral optical data representing in spatial (x, y) and spectral (λ) coordinates said object and said target species from the IR radiation received at the optical FPA unit.

Embodiment 201: The system of Embodiment 200, wherein the multispectral data comprises a number of spectrally different images of the object obtained from IR image data transferred to the optical FPA unit by a corresponding optical channel.

Embodiment 202: The system of any of Embodiments 200-201, further comprising an optical filter corresponding to a particular optical channel and configured to transmit the portion of IR radiation towards the optical FPA unit.

Embodiment 203: The system of any of Embodiments 200-202, wherein the optical filter includes one of a longpass optical filter and a shortpass optical filter.

Embodiment 204: The system of any of Embodiments 200-203, further comprising one or more front objective lenses.

Embodiment 205: The system of any of Embodiments 200-204, wherein the optical system comprises a plurality of lenses, each lens corresponding to an optical channel.

Embodiment 206: The system of any of Embodiments 200-205, wherein each optical channel is defined at least in part by a corresponding filter and a corresponding lens.

Embodiment 207: The system of any of Embodiments 200-206, wherein the plurality of lenses comprises a lens array.

Embodiment 208: The system of any of Embodiments 200-207, further comprising a plurality of relay lenses configured to relay the IR radiation along the optical channels.

Embodiment 209: The system of any of Embodiments 200-208, further comprising a plurality of moveable temperature-controlled reference source removably positioned to block IR radiation incident onto the optical system from reaching the optical FPA unit.

Embodiment 210: The system of any of Embodiments 200-209, wherein the multispectral optical data from the plurality of optical channels is captured substantially simultaneously by the optical FPA unit.

Embodiment 211: The system of any of Embodiments 200-210, wherein the multispectral optical data from the plurality of optical channels is captured during one image frame acquisition by the optical FPA unit.

Embodiment 212: The system of any of Embodiments 200-211, further comprising first and second temperature-controlled moveable shutters removably positioned to block IR radiation incident onto the optical system from reaching the optical FPA unit.

Embodiment 213: The system of any of Embodiments 200-212, wherein the optical FPA unit is devoid of a cooling device.

Embodiment 214: The system of any of Embodiments 200-213, further comprising a filter array.

Embodiment 215: The system of any of Embodiments 200-214, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to acquire said optical data from the two or more sets of imaging data.

Embodiment 216: The system of any of Embodiments 200-215, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to process the acquired optical data to compensate for at least one of (i) parallax-induced differences between the two or more sets of imaging data and (ii) difference between the two or more sets of imaging data induced by changes in the object that are not associated with the target species.

Embodiment 217: The system of any of Embodiments 200-216, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to process the acquired optical data to generate a temporal reference image.

Embodiment 218: The system of any of Embodiments 200-217, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to use the temporal reference image to generate a temporal difference image.

Embodiment 219: The system of any of Embodiments 200-218, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to process the acquired optical data to estimate a volume of a gas cloud.

Embodiment 220: The system of any of Embodiments 200-219, wherein IR radiation measured at a pixel comprises a spectrum comprising a sum of component spectra, and wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to unmix the spectrum.

Embodiment 221: The system of any of Embodiments 200-220, wherein the optical FPA unit includes a bolometer configured to operate without being cooled.

Embodiment 222: The system of any of Embodiments 200-221, further comprising a field reference for dynamically adjusting data output from the optical FPA unit.

Embodiment 223: The system of any of Embodiments 200-222, wherein the field reference comprises an array of field stops.

Embodiment 224: The system of any of Embodiments 200-223, wherein the field reference comprises a uniform temperature across its surface.

Embodiment 225: The system of any of Embodiments 200-224, wherein the field reference is adapted to obscure or block a peripheral portion of the IR radiation propagating from the object towards the optical FPA unit.

Embodiment 226: The system of any of Embodiments 200-225, further comprising a visible light imaging sensor.

Embodiment 227: The system of any of Embodiments 200-226, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to process data received from an imaging sensor to compensate for motion-induced imaging errors.

Embodiment 228: The system of any of Embodiments 200-227, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to process data received from the visible light imaging sensor to compensate for motion-induced imaging errors.

Embodiment 229: The system of any of Embodiments 200-228, wherein the processor is configured to execute instructions stored in a tangible, non-transitory computer-readable storage medium to construct, in the single occurrence of data acquisition, a multispectral data cube of the object, the multispectral data cube comprising a number of spectrally different images of the object, each spectrally different image comprising IR image data transferred to the optical FPA unit by a corresponding optical channel.

Embodiment 230: The system of any of Embodiments 200-229, wherein the portion of the IR radiation corresponds to a region of wavelengths of the spectrum of wavelengths, the region of wavelengths at least partially overlapping another region of wavelengths transferred by another optical channel.

Embodiment 231: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different optical channels, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object, andwherein the system is further configured to compare spectral data in at least one of the plurality of optical channels acquired at a first instant of time with spectral data in at least one of the plurality of optical channels acquired at a second instant of time to generate a temporal difference image.

Embodiment 232: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different optical channels, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object, andwherein the system is configured to use a difference between the multispectral optical data acquired by two optical channels to correct parallax-induced imaging errors.

Embodiment 232: The system of Embodiment 231, wherein spectral characteristics of the two optical channels are identical.

Embodiment 233: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different optical channels, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object, andwherein the system is configured to use a difference between the multispectral optical data acquired by two optical channels to estimate a distance between the system and the object.

Embodiment 234: The system of Embodiment 233, wherein spectral characteristics of the two optical channels are identical.

Embodiment 235: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different optical, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit;a visible light imaging sensor; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object.

Embodiment 236: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different optical, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object, andwherein the system is configured to compensate for motion-induced imaging errors.

Embodiment 237: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object by cross-correlating multispectral optical data from at least one of the optical channels with a reference spectrum.

Embodiment 238: An infrared (IR) imaging system, the imaging system comprising:a plurality of spatially and spectrally different optical, at least some of the plurality of optical channels configured to receive IR radiation from a common object, each of the plurality of spatially and spectrally different optical channels comprising at least one imaging lens configured to image the object on a Focal Plane Array (FPA) unit; andprocessing electronics in communication with the FPA unit,wherein said infrared system is configured to:acquire multispectral optical data from the plurality of different optical channels; andprocess the multispectral optical data to detect one or more target species present in the object by using spectral unmixing.

Embodiment 239: An infrared (IR) imaging system, the imaging system comprising:an optical system including an optical focal plane array (FPA) unit, the optical system includes components associated with at least two optical channels, said at least two optical channels being spatially and spectrally different from one another, each of the at least two optical channels positioned to transfer IR radiation incident on the optical system towards the optical FPA unit, the optical FPA unit comprising at least two detector arrays disposed at a distance from two corresponding focusing lenses;at least one thermal reference having a known temperature, wherein one of the at least two detector arrays is configured to image the at least one reference; anda data-processing unit, said data-processing unit configured to:acquire a plurality of frames with one of the at least two detector arrays having regions in the plurality of image frames that correspond to the image of the reference; anddynamically calibrate another of the at least two detector array to match a temperature estimate of another of the at least two detector array with the temperature estimate of one of the at least two detector array.

Embodiment 240: The system of any of Embodiments 1-59, wherein the plurality of cameras are configured to acquire multispectral image data from an object continuously for a duration of time.

Embodiment 241: The system of any of Embodiments 1-59, comprising at least two spectrally and spatially distinct optical channels configured to transfer two-dimensional image data of an object to the plurality of cameras.

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

