13 September 1994 Cold box subsystem for the infrared atmospheric sounding interferometer (IASI) instrument: payload for the METOP-1 ESA polar platform
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IASI is an Infrared Atmospheric Sounding Interferometer devoted to the operational meteorology and to atmospheric studies and is to be installed on-board the second ESA Polar Platform called METOP-1; It is planned to be launched in the year 2000. The required operating lifetime is 4 years with a target of 7 years plus 4 years of ground storage. The cold Optical Unit is located at the focal plane of the Michelson Interferometer. This sub-assembly is designed to divide the IR input flux into 3 spectral bands and to focus it on the 3 arrays of detection. It includes a spectral separation using 2 beam splitters dividing the incoming flux into 3 spectral bands which are 3.4 to 5.0 micrometers , 5.0 to 8.26 micrometers and 8.26 to 15.5 micrometers . Each array stands behind an objective and a set of 4 microlenses. This unit defined the aperture and the field of view of the instrument and operates at 100 K with passive cooling. An overall design of the cold box has been performed for the mechanical structure and for the optics taking into account the space requirements. This structure is interfaced with a passive radiator and is illustrated by several figures. A thermal analysis of this unit has been computed to check the thermal gradient by means of a finite-element software involving several thousands of nodes. A specific optical ray tracer delivered the optimization and the tolerancing of the optical design. The results show that, with severe tolerances, the optical losses and cross-talk meet the requirements. The optical diagram has been drawn, as well as the CNES instrument design. Several critical items have been manufactured to check that they can meet the required performance (photoconductive detectors, microlenses, AR coatings, packaging).
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Michel Royer, Michel Royer, Bruno Fauquier, Bruno Fauquier, Jean Feuvrier, Jean Feuvrier, Pierre Froissart, Pierre Froissart, Pierre Etcheto, Pierre Etcheto, Christian Buil, Christian Buil, } "Cold box subsystem for the infrared atmospheric sounding interferometer (IASI) instrument: payload for the METOP-1 ESA polar platform", Proc. SPIE 2209, Space Optics 1994: Earth Observation and Astronomy, (13 September 1994); doi: 10.1117/12.185258; https://doi.org/10.1117/12.185258


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