157nm是对硬脆材料进行激光表面微加工的理想波段。构建数学模型以探讨激光抛光材料时工艺参数对表面粗糙度Ra的影响,使用最小二乘法推导出粗糙度的计算式。利用157nm激光对GaN外延片进行了抛光微加工的基础实验。通过比较多组模拟与实验粗糙度值,发现理论粗糙度值与实际的测量值之间有一定误差,但相对误差都在15%以下,最小的相对误差为4%。以低于15Hz的脉冲频率和高于0.7mm/min的扫描速度进行激光扫描刻蚀时,可以获得较低的表面粗糙度。数学模型合理地解释了抛光后底面沟壑的形成,为今后改善加工质量提供了理论依据。 157nm is ideal for laser micro-machining of hard and brittle materials. Mathematical model was constructed to investigate the effect of technological parameters on the Ra of the surface roughness of the laser polishing material, and the formula of roughness was deduced by the least squares method. Using 157nm laser on GaN epitaxial wafers polished micro-processing of the basic experiment. By comparing several sets of simulation and experimental roughness values, it is found that there is a certain error between the theoretical roughness value and the actual measurement value, but the relative error is below 15% and the minimum relative error is 4%. Lower surface roughness can be achieved with laser scanning etching at pulse frequencies below 15 Hz and scanning speeds above 0.7 mm / min. The mathematic model reasonably explains the formation of ground gully after polishing, which provides a theoretical basis for improving the processing quality in the future.