JWST NIRSpec Cryogenic Light Shield Mechanism

Abstract

The focal plane detectors for the Near-Infrared Spectrometer (NIRSpec) instrument on the James Webb Space Telescope (JWST) require a light tight cover for calibration as well as an open field-of-view during ground performance testing within a cryogenic dewar. In order to achieve the light attenuation requirements when closed as well as provide a open field of view for the detectors within the cryogenic dewar, a light shield mechanism was designed. This paper discusses the details of the light shield mechanism design, development, and test results.