Cryocooled optics and contamination

This paper is a survey of several cryogenic effects on optical components and the problems associated with operation of optical systems at cryogenic temperatures. These potential problem areas evolved, in most cases, from operational difficulties in large cryogenically cooled space test chambers and were studied experimentally in smaller research laboratory chambers. The specific areas discussed are the temperature sensitivity of the complex refractive index, the usage of polystyrene as a wavelength calibrator at 20 K, the transmittance and reflectance changes with temperature, the infrared spectra of typical condensed gases on a cryogenic window, and the use and calibration of the blackbodies at temperatures below 400 K.