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Proceedings Paper

Geometrical misalignment retrieval of the IASI interferometer
Author(s): Francois Henault; Philippe-Jean Hebert; Christophe Lucchini; Didier Miras
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Paper Abstract

The IASI instrument (Infrared Atmospheric Sounding Interferometer) is a Fourier-Transform Spectrometer (FTS) providing spectra of the Earth's atmosphere observed from space. The heart of the instrument is a Michelson interferometer (IHOS) equipped with two hollow cube-corners retro-reflectors in place of the classical flat mirrors. The main alignment requirements of the IASI interferometer are the lateral shift, or shear, of the moving cube-corner (seen through the beamsplitter) and the misalignment of its scanning axis: these contributions should not exceed 20 micrometer and 250 (mu) rad respectively during the five years mission in orbit. Thus the most difficult challenge of the IHOS integration on-ground probably is their measurement accuracy, which shall respectively be better than 1 micrometer and 100 (mu) rad. The envisaged characterization method consists in a specific data processing of the fringe patterns created by the interferometer at four different points located in the IHOS Field of View (FoV), corresponding to the IASI instrument pixels. For each acquired interferogram the Optical Path Difference (OPD) created by the interferometer are evaluated using a double Fourier-transform algorithm, and the results are combined together in order to retrieve the apparent trajectory of the mobile cube-corner. This principle was tested on a breadboard interferometer already assembled in the CNES laboratories. The numerical results presented herein tend to demonstrate the efficiency of the method, since the achieved accuracy does not exceed 1.2 micrometer (whatever the cube-corner axial position) and 120 (mu) rad respectively. The main error sources also are discussed.

Paper Details

Date Published: 28 December 1999
PDF: 12 pages
Proc. SPIE 3870, Sensors, Systems, and Next-Generation Satellites III, (28 December 1999); doi: 10.1117/12.373174
Show Author Affiliations
Francois Henault, Alcatel (France)
Philippe-Jean Hebert, CNES (France)
Christophe Lucchini, Alcatel (France)
Didier Miras, Alcatel (France)

Published in SPIE Proceedings Vol. 3870:
Sensors, Systems, and Next-Generation Satellites III
Hiroyuki Fujisada; Joan B. Lurie, Editor(s)

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