Infrared measurements of possible IR filter materials

A Fourier Transform Infrared Spectrometer (FTS) was used to obtain the transmission spectra of candidate materials for use as infrared (IR) filters in cryogenic receivers. The data cover the range from 50 cm−1 (∼1.5 THz), well below the peak of the 300 K black body spectrum, to 5000 cm−1 (∼150 THz), Z-cut quartz, Goretex, Zitex G and Zitex A, High Density Polyethylene (HDPE), Teflon (PTFE), Fluorogold and Black Polyethylene were measured. The relative effectiveness of each material as a filter is determined by integrating the transmission spectrum multiplied by the Planck distribution to obtain a normalized attenuation for the mid-IR band. Measurements at both room temperature and 8 K are compared.