Characterization of the reflected beam profile of solar mirror materials

Abstract The absolute specular reflectance of flat mirrors was obtained as a function of the reflected beam width from 1 mrad to 17 mrad using a bidirectional reflectometer. The characteristics, calibration and advantages of this reflectometer are discussed. The mirror materials studied include samples of silvered glass, metallized plastic films and polished, bulk aluminum obtained from a variety of commerical suppliers. For some of these materials, the reflected beam profile could be described by a single normal distribution. However, for the other materials, the reflected beam profile was described by the sum of two normal distributions. Examples of the curve fitting procedure and data for selected materials are presented.