The Cryogenic Refocusing Mechanism of NIRSpec OPTO-MECHANICAL DESIGN, ANALYSIS AND TESTING

摘要

A novel cryogenic refocusing mechanism (RMA) has been designed by Galileo Avionica (GA) for the Near Infra-Red Spectrograph (NIRSpec), one of the instruments of the James Webb Space Telescope (JWST). The RMA shall correct possible in orbit focal length variations by a rigid translation of a set of two mirrors in a 6 mm range, with an accuracy of 50 microns and 15 microns step size. The RMA development has been driven by the operation at 30K. temperature while being still fully functional at room temperature, by the need to incorporate two mirrors with demanding quality as part of the mechanism and by tight envelope constraints.This paper reports details of the RMA opto-mechanical design and analysis and about the dedicated optical set-up developed for its verification..