James Webb Space Telescope optical simulation testbed IV: linear control alignment of the primary segmented mirror

Sylvain Egron; Rémi Soummer; Charles-Philippe Lajoie; Aurélie Bonnefois; Joseph Long; Vincent Michau; Elodie Choquet; Marc Ferrari; Lucie Leboulleux; Olivier Levecq; Johan Mazoyer; Mamadou N'Diaye; Marshall Perrin; Peter Petrone; Laurent Pueyo; Anand Sivaramakrishnan

doi:10.1117/12.2272981

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5 September 2017 James Webb Space Telescope optical simulation testbed IV: linear control alignment of the primary segmented mirror

Sylvain Egron, Rémi Soummer, Charles-Philippe Lajoie, Aurélie Bonnefois, Joseph Long, Vincent Michau, Elodie Choquet, Marc Ferrari, Lucie Leboulleux, Olivier Levecq, Johan Mazoyer, Mamadou N'Diaye, Marshall Perrin, Peter Petrone, Laurent Pueyo, Anand Sivaramakrishnan

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Proceedings Volume 10398, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VIII; 1039811 (2017) https://doi.org/10.1117/12.2272981
Event: SPIE Optical Engineering + Applications, 2017, San Diego, California, United States

Abstract

The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop experiment designed to study wavefront sensing and control for a segmented space telescope, such as JWST. With the JWST Science and Operations Center co-located at STScI, JOST was developed to provide both a platform for staff training and to test alternate wavefront sensing and control strategies for independent validation or future improvements beyond the baseline operations. The design of JOST reproduces the physics of JWST’s three-mirror anastigmat (TMA) using three custom aspheric lenses. It provides similar quality image as JWST (80% Strehl ratio) over a field equivalent to a NIRCam module, but at 633 nm. An Iris AO segmented mirror stands for the segmented primary mirror of JWST. Actuators allow us to control (1) the 18 segments of the segmented mirror in piston, tip, tilt and (2) the second lens, which stands for the secondary mirror, in tip, tilt and x, y, z positions. We present the most recent experimental results for the segmented mirror alignment. Our implementation of the Wavefront Sensing (WFS) algorithms using phase diversity is tested on simulation and experimentally. The wavefront control (WFC) algorithms, which rely on a linear model for optical aberrations induced by misalignment of the secondary lens and the segmented mirror, are tested and validated both on simulations and experimentally. In this proceeding, we present the performance of the full active optic control loop in presence of perturbations on the segmented mirror, and we detail the quality of the alignment correction.

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Sylvain Egron, Rémi Soummer, Charles-Philippe Lajoie, Aurélie Bonnefois, Joseph Long, Vincent Michau, Elodie Choquet, Marc Ferrari, Lucie Leboulleux, Olivier Levecq, Johan Mazoyer, Mamadou N'Diaye, Marshall Perrin, Peter Petrone, Laurent Pueyo, and Anand Sivaramakrishnan "James Webb Space Telescope optical simulation testbed IV: linear control alignment of the primary segmented mirror", Proc. SPIE 10398, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VIII, 1039811 (5 September 2017); https://doi.org/10.1117/12.2272981

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