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New Thermal Infrared Hyperspectral Imagers

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The aim for this paper is to present designs and performance characteristics of the new push-broom hyperspectral imagers in thermal wavelength region. The guiding motive for this work has been to design high performance instruments with good image quality, compact size and easy operation for different application requirements. The studies involve imaging systems based on both MCT and microbolometer detector. All the systems base on push-broom imaging spectrograph with transmission grating and on-axis optics. Two instruments have been developed for LWIR wavelength range, 8 V 12 gm. The airborne remote sensing imager utilizes MCT detector combined with BMC-technique background monitoring on-chip, background suppression and temperature stabilization. This instrument provides high performance suitable for airborne and on-the-field remote sensing applications. The performance of the imager with 84 spectral bands and 384 spatial samples has been studied and NESR of 18 mWm2sr m at 10 m wavelength for 300 K target has been achieved. This leads to SNR of 580. These results are based on a simulation models. Realizing these goals without considerable cooling of the whole instrument is a challenging task. The key issue in the design is to control the instrument radiation falling on the detector from all the surfaces of the instrument itself. Consequences of the instrument radiation are raising background level and reduction in dynamic range. This challenge is particularly prominent in hyperspectral instruments, where the optical power from the target is spread spectrally over tens of pixels, but the instrument radiation is not dispersed. Without suppression, the instrument radiation may exceed the radiation incident from the target by several orders of magnitude. The same principles applied to the LWIR hyperspectral imager, are applicable in the case of MWIR, 3 V 5 gm, wavelength region.

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  • Atomic and Molecular Physics and Spectroscopy

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