Design and Manufacturing Technologies for All-Reflective Collimators, Relays, and Derotating Assemblies in Cryovac Instruments

摘要

Aluminum mirrors are in increasingly common use for low background cryogenic radiometers, spectrometers, telescopes, collimators, scene generators, and black body reference targets used in the contexts of research in astronomy, and sensor system calibration and simulation. Reflective aluminum systems are relatively low cost, provide broadband performance, high thermal conductivity, and exceptionally isotropic thermal contraction. Aluminum optics may be net diamond point machined or nickel plated and post polished to yield more refined tolerances for surface figure and surface finish. Nickel plated mirrors must neutralize the influences of bi-metal interfaces over a large reduction in temperature. General design and manufacturing guidelines applied to three actual, and widely varied cryogenic reflective assemblies are presented. These applications were shown respectively to exhibit diffraction-limited performance in the range of 0.80-1.5 micron at cryogenic temperatures ranging from 20°K to 80°K.