Thermal Cycling Effects On The BRDF Of Beryllium Mirrors

The effects of extreme changes in temperature on the Bi-directional Reflectance Distribution Function (BRDF) of beryllium mirrors have been observed and measured using an unique infrared (10.6-micron) scatterometer [1]. This paper describes the experimental apparatus and procedures, qualifies its accuracy and repeatability, and presents the BRDF data taken on two Be mirrors, at 300 K and 20 K, during repeated thermal cycling.