Space environment challenges with the tunable Fabry-Perot etalon for the JWST fine guidance sensor

Craig Haley; Niladri Roy; Zeljko Osman; Neil Rowlands; Alan Scott

doi:10.1117/12.927026

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21 September 2012 Space environment challenges with the tunable Fabry-Pérot etalon for the JWST fine guidance sensor

Craig Haley, Niladri Roy, Zeljko Osman, Neil Rowlands, Alan Scott

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Proceedings Volume 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave; 84423M (2012) https://doi.org/10.1117/12.927026
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

The Fine Guidance Sensor (FGS) on the James Webb Space Telescope (JWST) has a science observing capability that was to be provided by a tunable Fabry-Pérot etalon incorporating dielectric coated etalon plates with a small vacuum gap and piezoelectric actuators (PZTs). The JWST etalon was more challenging than our existing ground-based operational systems due to the low-order gap, the extremely wide waveband and the environmental specifications. Difficulties were encountered in providing the required performance due to variability in the mechanical gap after exposure to the vibration, shock and cryogenic cycling environments required for the JWST mission. The risks associated with operating the flight model etalon in the space environment, along with changes in scientific priorities, resulted in the etalon being replaced by the grism-based Near-Infrared Imager and Slitless Spectrograph (NIRISS). We describe here the performance of the etalon system and the unresolved risks that contributed to the decision to change the flight instrument.

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Craig Haley, Niladri Roy, Zeljko Osman, Neil Rowlands, and Alan Scott "Space environment challenges with the tunable Fabry-Pérot etalon for the JWST fine guidance sensor", Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84423M (21 September 2012); https://doi.org/10.1117/12.927026

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