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Proceedings Paper

Effects of thermal deformations on the sensitivity of optical systems for space application
Author(s): Elisa Segato; Vania Da Deppo; Stefano Debei; Gabriele Cremonese; Giovanni Cherubini
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Paper Abstract

In this paper the results of the thermo-elastic analysis performed on the Stereo Imaging Channel of the imaging system SIMBIO-SYS for the BepiColombo ESA mission to Mercury is presented. The aim of the work is to determine the expected stereo reconstruction accuracy of the surface of the planet Mercury, i.e. the target of BepiColombo mission, due to the effects of the optics misalignments and deformations induced by temperature changes during the mission lifetime. The camera optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) program, which reproduces the expected optics and structure thermo-elastic variations in the instrument foreseen operative temperature range, i.e. between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: a non-linear least square algorithm is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into ZEMAX raytracing code for sequential raytrace analysis. Variations of the optical center position, boresight direction, focal length and distortion are then computed together with the corresponding image shift on the detector. The overall analysis shows the preferable use of kinematic constraints, instead of glue classical solution, for optical element mountings, this minimize the uncertainty on the Mercury Digital Terrain Model (DTM) reconstructed via a stereo-vision algorithm based on the triangulation from two optical channels.

Paper Details

Date Published: 4 August 2010
PDF: 13 pages
Proc. SPIE 7738, Modeling, Systems Engineering, and Project Management for Astronomy IV, 773806 (4 August 2010); doi: 10.1117/12.855746
Show Author Affiliations
Elisa Segato, CISAS G. Colombo (Italy)
Vania Da Deppo, CNR-IFN UOS (Italy)
Stefano Debei, Univ. degli Studi di Padova (Italy)
Gabriele Cremonese, INAF-Osservatorio Astronomico di Padova (Italy)
Giovanni Cherubini, SELEX Galileo (Italy)

Published in SPIE Proceedings Vol. 7738:
Modeling, Systems Engineering, and Project Management for Astronomy IV
George Z. Angeli; Philippe Dierickx, Editor(s)

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