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

摘要

The Fine Guidance Sensor (FGS) on the James Webb Space Telescope (JWST) has a science observing capability thatwas to be provided by a tunable Fabry-Pérot etalon incorporating dielectric coated etalon plates with a small vacuum gapand piezoelectric actuators (PZTs). The JWST etalon was more challenging than our existing ground-based operationalsystems due to the low-order gap, the extremely wide waveband and the environmental specifications. Difficulties wereencountered in providing the required performance due to variability in the mechanical gap after exposure to thevibration, shock and cryogenic cycling environments required for the JWST mission. The risks associated withoperating the flight model etalon in the space environment, along with changes in scientific priorities, resulted in theetalon being replaced by the grism-based Near-Infrared Imager and Slitless Spectrograph (NIRISS). We describe herethe performance of the etalon system and the unresolved risks that contributed to the decision to change the flightinstrument.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.