Simulation and detection of surface defects of optical components

Surface defect detection is the key to assessing the quality of optical surfaces. Traditional geometric optics cannot adequately explain the distribution of defects on surfaces. Herein, a method is proposed to comprehensively investigate the scattering characteristics of surface defects in precision optical components. First, electromagnetic theoretical models of surface defects with cross-sections of triangles, ellipses, and rectangles were established using the finite element method. Through simulation, the precise distribution of scattered light at the micro-nano-scale defects in the transmissive-reflective direction was obtained. Subsequently, a sophisticated dark-field microscopic testing system was designed and constructed to capture high-resolution scattered light images of standard defect samples. To effectively measure the depth of surface defects, a highly sensitive photomultiplier tube was used to measure the scattered light intensity. The measured intensity was subsequently compared with the theoretical simulation results to obtain a reference value for the defect depth. The reference values for the depth of surface defects obtained from the simulation are largely consistent with experimental results. It provides a theoretical foundation and reference for the multidimensional measurement of surface defects in optical components.