DUAL-BAND DIVIDED-APERTURE INFRA-RED SPECTRAL IMAGING SYSTEM
Various embodiments disclosed herein describe a divided-aperture infrared spectral imaging (DAISI) system that is adapted to acquire multiple IR images of a scene with a single-shot (also referred to as a snapshot). The plurality of acquired images having different wavelength compositions that are obtained generally simultaneously. The system includes at least two optical channels that are spatially and spectrally different from one another. Each of the at least two optical channels are configured to transfer IR radiation incident on the optical system towards an optical FPA unit comprising at least two detector arrays. One of the at least two detector arrays comprises a cooled mid-wavelength infra-red FPA. The system further comprises at least one temperature reference source or surface that is used to dynamically calibrate the two detector arrays and compensate for a temperature difference between the two detector arrays.
1 . An infrared (IR) imaging system for imaging a scene, the imaging system comprising:
an optical system comprising an optical focal plane array (FPA) unit including a plurality of spatially and spectrally different optical channels to transfer IR radiation from the scene towards the optical FPA unit, each optical channel positioned to transfer a portion of the IR radiation incident on the optical system from the scene towards the optical FPA unit,
wherein at least one of the plurality of optical channels is in the mid-wavelength infrared spectral range and at least another one of the plurality of optical channels is in the long-wavelength infrared spectral range,
wherein the imaging system is configured to acquire a first video image of the scene in the mid-wavelength infrared spectral range and a second video image of the scene in the long-wavelength infrared spectral range.
2 . The imaging system of claim 1 , wherein the at least one mid-wavelength optical channel comprises a cold stop filter.
3 . The imaging system of claim 1 , wherein the at least one mid-wavelength optical channel comprises filter having a pass-band in the mid-wavelength infrared spectral range.
4 . The imaging system of claim 1 , further comprising processing electronics configured to extract information from the first and second video image to detect presence of one or more chemical species in the scene.
5 . The imaging system of claim 4 , wherein the processing electronics are configured to compare the extracted information to one or more spectral information stored in a database.
6 . The imaging system of claim 1 , further comprising a feedback system configured to synchronize the first and the second video image.
7 . The imaging system of claim 1 , wherein the first and/or second video image has a frame rate between about 5 frames per second and about 120 frames per second.
8 . The imaging system of claim 1 , wherein the processing electronics are configured to extract information from the first and/or second video image on a frame by frame basis.
9 . The imaging system of claim 1 , wherein the processing electronics are configured to extract information from the first video and second video image and detect presence of one or more chemical species in the scene within 5 seconds from a time when imaging of the scene started.
10 . The imaging system of claim 1 , wherein the processing electronics are configured to extract information from the first video and second video image and detect presence of one or more chemical species in the scene within 1 second from a time when imaging of the scene started.
11 . The imaging system of claim 1 , wherein the processing electronics are configured to extract information from the first video and second video image and detect presence of one or more chemical species in the scene in sufficiently real time from a time when imaging of the scene started.
12 . The imaging system of claim 1 , wherein the one or more chemical species are selected from the group consisting of methane, cyclopropane, alkanes, alkenes, ammonia, freon, hydrogen cyanide, sulfur dioxide, and hydrogen sulfide.
13 . The imaging system of claim 1 , wherein the scene includes a moving gas plume.
14 . The imaging system of claim 1 , wherein the FPA unit includes at least one mid-wavelength infra-red FPA capable of detecting mid-wavelength infra-red radiation and at least one long-wavelength infra-red FPA capable of detecting long-wavelength infra-red radiation.
15 . The imaging system of claim 14 , wherein the at least one mid-wavelength infra-red FPA is cooled to a temperature below 200 degree Kelvin.
16 . The imaging system of claim 15 , wherein the at least one mid-wavelength infra-red FPA is cooled to a temperature between about 110 degree Kelvin and about 150 degree Kelvin.
17 . The imaging system of claim 16 , wherein the at least one mid-wavelength infra-red FPA is cooled to a temperature of about 135 degree Kelvin.
18 . The imaging system of claim 14 , wherein the at least one mid-wavelength infra-red FPA is coupled to a cooler.
19 . The imaging system of claim 14 , wherein the at least one mid-wavelength infra-red FPA and the at least one long-wavelength infra-red FPA are configured to image one more reference sources.
20 .- 35 . (canceled)
36 . A method of detecting one or more chemical species in a scene, the method comprising:
obtaining a first video image data of the scene in mid-wavelength infrared spectral range using a mid-wavelength infra-red FPA;
obtaining a second video image data of the scene in long-wavelength infrared spectral range using a long-wavelength infra-red FPA;
obtaining one or more spectra from the first and the second video image data; and
comparing the obtained one or more spectra with one or more reference spectra stored in a database to detect one or more chemical species in the scene.
37 .- 42 . (canceled)