上海科技大学知识管理系统

Surface defects have a modulation effect on the distribution of the incident laser electric field, which limits the improvement of the laser damage threshold of optical elements, and threatens the security and stability of strong laser system. To evaluate the light field modulation caused by smaller size defects on precision optical surface upon current processing technology, several detections and numerical simulations of the defects are conducted. By measuring and counting scratches' depth and width on the surface of large-aperture neodymium glass, the distribution upon current processing technology is obtained. According to the above parameters, numerically simulating the surrounding electric field distribution of surface scratch similar to the real is performed by the finite difference time domain (FDTD) method. The results show that when the width is constant, as the depth is within 300nm, the maximum near-field electric field intensity in the scratch area is gradually increased with the increase of the depth; when the depth is constant, as the width is larger than 30μm the maximum near-field electric field intensity modulated by scratched area is inversely proportional to its width. Meanwhile, the influence of electric field distribution modulation on the surface of the optical element is in a relatively stable range as the ratio of the depth and width of scratches is under 0.15. With the raise of the ratio, the modulation effect on the surface electric field is rapidly enhanced. The research results provide some support for surface defects control and processing technology improvement. © 2023 SPIE.