Establishment and verification of sub-aperture scanning Fourier transform system for scattered light measurements

We present sub-aperture scanning Fourier transform system, a method for fast Bidirectional reflection distribution function (BRDF) measurements. A single lens is used for Fourier transform, and the scattering light field is measured by sub aperture scanning of the Fourier transform lens. Through Fourier transform, a single measurement can obtain multi-angle scattering data, and sub-aperture scanning further expands the measurement angle range. Due to the full utilization of image detectors, once measurement can get 1944 points’ data inside 10°. Thus the system's precision can get to 0.005°and the measurement time can shorten ten times. Finally, the method is verified by comparing the experimental data. Experimental results show that the relative error of this method is less than 1%. These results provide theoretical basis and technical support for the application of BRDF in sub aperture scanning Fourier transform system.