In situ laser reflectance measurement of diffuse surfaces

Report is made on an in situ method of laser reflectance measurement of diffuse surfaces by using a GaAs laser and off-the-shelf optical components not involving radiation integration over a hemisphere as with most conventional reflectometers. The design features and limitations are described. Several diffuse surfaces were evaluated by this method, and the reflectance results obtained were in good agreement with those determined by the method of integrating sphere that used MgCO(3) surface as a standard. The main advantages of this method are: the elimination of the need of a surface standard; the avoidance of having the surfaces in close contact with the measuring equipment; the accuracy better than 10%; and the relatively straightforward alignment.