Experimental ray-tracing with point diffraction interferometry and its application in focal length measurement

A novel method that could experimentally trace the ray propagation of an optical system based on point diffraction interferometry (PDI) is presented. The ray represented by the line connecting two point light sources (PLS) intersects with two parallel photographic planes, which are separated at a distance. The intersections of the ray defined by the PLSs with the planes occur where the optical path difference is a maximum and can be determined from interferograms on the photographic planes. The ray is determined by connecting the two intersections. Using fibers as the PLSs and CCD arrays as the photographic planes, we demonstrate its principle and its application in focal length measurement through experiments.