AN APPARATUS FOR INFRARED TRANSMITTANCE AND REFLECTANCE MEASUREMENTS AT CRYOGENIC TEMPERATURES

A facility for measuring the optical properties of solid materials at cryogenic temperatures is bring developed at the National Institute of Standards and Technology. A cryostat that houses four bolometric dete ctors and a six-position sample holder was designed and built. The bol ometers operate near 5 K, and the sample temperature can be varied fro m 6 to 100 K. The beam from a Fourier transform spectrometer is direct ed to the cryostat by reflective optical components. The measurable wa velengths extend from 1 mu m to 1 mm, with appropriate sources and bea msplitters in the spectrometer as well as as windows and detectors in the cryostat. Thr angle of incidence on the sample ranges from 7.5 to 60 degrees. The mechanical, electrical, and optical designs are descri bed in this paper. Initial measurement results at wavelengths from 2 t o 30 mu m and a sample temperature of 10 K are presented.