PROCEDURES FOR PRECISE DETERMINATION OF THERMAL RADIATION PROPERTIES, NOVEMBER 1963 TO OCTOBER 1964.
NATIONAL BUREAU OF STANDARDS WASHINGTON D C
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A laser-source integrating sphere reflectometer was designed and built to measure the reflectance of specimens at high temperatures. The sphere was calibrated for linearity of response of 0.632 microns by means of a shallow cylindrical cavity with a variable depth-toradius ratio, having a lining of known reflectance. Preliminary tests showed that the flux emitted by a hot specimen at temperatures up to 2500 K will not invalidate the reflectance measurement. An ellipsoidal mirror reflectometer was calibrated for all known errors in the 1 to 7.5 microns range. A preliminary analysis indicates that the errors in measurement of absolute reflectance with this equipment should not exceed 2 percent. A review of the literature on relation of thermal radiation properties to other properties of materials is presented, together with a summary of the work done in an effort to compute the spectral emittance of rhodium. Author