Effects of thermal deformations on the sensitivity of optical systems for space application

Elisa Segato; Vania Da Deppo; Stefano Debei; Gabriele Cremonese; Giovanni Cherubini

doi:10.1117/12.855746

4 August 2010 Effects of thermal deformations on the sensitivity of optical systems for space application

Elisa Segato, Vania Da Deppo, Stefano Debei, Gabriele Cremonese, Giovanni Cherubini

Proceedings Volume 7738, Modeling, Systems Engineering, and Project Management for Astronomy IV; 773806 (2010) https://doi.org/10.1117/12.855746
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

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, n^th 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.

Citation Download Citation

Elisa Segato, Vania Da Deppo, Stefano Debei, Gabriele Cremonese, and Giovanni Cherubini "Effects of thermal deformations on the sensitivity of optical systems for space application", Proc. SPIE 7738, Modeling, Systems Engineering, and Project Management for Astronomy IV, 773806 (4 August 2010); https://doi.org/10.1117/12.855746

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