From Event: SPIE Optical Engineering + Applications, 2019
Infrared Fourier-transform spectrometers (FTIR) onboard of the planetary missions are commonly used for the thermal sounding of the atmosphere and retrieval of aerosol profiles. To derive a calibrated spectrum of the target source, one needs three separate measurements: the target source itself and two calibration measurements of sources with known emissivity and temperature. An overview of the design of a compact in-built calibration source (a blackbody) emitting at 210-330 K for a spaceborne FTIR instrument is presented. Mechanically it is an aluminum structure matching the aperture of the instrument. The emissivity depends on its surface relief and finish. Four different types of surface shape are considered. The best-achieved emissivity is better than 0.99 (at 15 μm). The optimal placement of heaters allowing for minimal thermal non-uniformity (0.1 K) across the aperture is found. The accuracy of the thermal control is also ~0.1 K. We discuss the thermal control system and its characteristics (accuracy and drift). The proposed design accounts for a minimum mass applicable to the space instrumentation. For a one-inch aperture, the mass is 0.12 kg. The expected accuracy of the instrument calibrated with the designed blackbody is estimated.
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Alexey Shakun, Fedor Martynovich, Nikolay Ignatiev, Alessandro Maturilli, Aleksandr Santos-Skripko, Vladimir Savosin, Igor Stupin, Gabriele Arnold, Alexei Grigoriev, and Oleg Korablev, "Compact calibration source for thermal infrared Fourier-transform spectrometer," Proc. SPIE 11128, Infrared Remote Sensing and Instrumentation XXVII, 1112803 (Presented at SPIE Optical Engineering + Applications: August 12, 2019; Published: 9 September 2019); https://doi.org/10.1117/12.2528692.