Cryogenic metrology for the James Webb Space Telescope Integrated Science Instrument Module alignment target fixtures using laser radar through a chamber window

摘要

The James Webb Space Telescope Integrated Science Instrument Module utilizes two fixtures to align the Optical Telescope Element Simulator (OSIM) to the coordinate systems established on the ISIM and the ISIM Test Platform (ITP). These fixtures contain targets which are visible to the OSIM Alignment Diagnostics Module (ADM). Requirements on these fixtures must be met under ambient and cryogenic conditions. This paper discusses the cryogenic metrology involving Laser Radar measurements through a chamber window that will be used to link photogrammetry target measurements used during ISIM structure cryogenic verification and the ADM targets, including evaluation of distortion introduced from the window.