Stray light modeling of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM)

Abstract

This paper describes an integrated stray light model of each Science Instrument (SI) in the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) and the Optical Telescope Element Simulator (OSIM), the light source used to characterize the performance of ISIM in cryogenic-vacuum tests at the Goddard Space Flight Center (GSFC). We present three cases where this stray light model was integral to solving questions that arose during the testing campaign -1) ghosting and coherent diffraction from hardware surfaces in the Near Infrared Imager and Slitless Spectrograph (NIRISS) GR700XD grism mode, 2) ghost spots in the Near Infrared Camera (NIRCam) GRISM modes, and 3) scattering from knife edges of the NIRCam focal plane array masks.

Designing a new, large, complex observatory: learning the strategic lesson of newness from our experience on the James Webb Space Telescope

“…As such, the stray light performance of Webb was well studied through the design phase of the program 9 , 10 , 36 – 41 Figure 8 presents the verification plan for stray light, circa 2016. It features a number of analyses and cross checks.…”

Metrology for trending alignment of the James Webb Space Telescope before and after ambient environmental testing

“…In the fall of 2016 the ISIM was integrated to the OTE and met its ambient alignment requirements. ISIM had undergone rigorous characterizations and environmental testing on its own 1,2,3,4,5,6 . After ISIM and the OTE (OTIS) were integrated, the OTIS was required to experience both vibration (for three orientations) and acoustics testing.…”