A goniometric light scattering instrument with high-resolution imaging

This paper describes a new goniometric optical scattering instrument whose distinctive features include a mobile light source, a telecentric objective, and a fixed photodiode array. A scientific-grade CCD detector allows the instrument to reliably detect BRDF levels as low as 5×10-8sr-1, while generating a high-resolution map of light scattered from the sample surface. These data reveal the position and size of localized defects, which can then be excised from the sample to give an unbiased determination of the surface’s intrinsic roughness. High-quality signature and calibration data are also obtained, as well as a practical characterization of a silicon wafer.