Infrared Reflectance and Refractive Index Measurements in Vacuum-Rated Hemiellipsoidal Mirror Reflectometer from 20 to 300 K

摘要

Experimental studies have been carried out for determining the change in reflectance caused by the condensation of thin films on 77 and 20 deg. K mirror surfaces in the 20 to 25 microns wavelength range. Refractive indices of the gases condensed were measured at the He-Ne laser wavelength, 0.6328 microns. Hemispherical-directional reflectance measurements of the mirror-condensed gas composites were made using a hemiellipsoidal mirror reflectometer system. The refractive index and reflectance of condensed films of N2, O2, CO2, H2O, NH3, N2O, NO, CO, CH4, argon, air, and allene were measured. Thicknesses and refractive indices were determined using the two-angle interference technique. In addition to the reflectance measurements made on cryogenic samples, an interfacility comparison of relfectance measurements was made on several anodized metal coatings at room temperature using reflectometers at the Air Force Materials Laboratory at Wright-Patterson Air Force Base, the Convair Division of General Dynamics Corporation in San Diego, and at AEDC. Reflectance measurements were also made on a variety of salt samples (such as nitrates, sulfates, and chlorides) at room temeprature and at 77 K to demonstrate the applications available for the HEMR. (Author)