亚表面损伤深度测量的理论研究与实验分析

Theoretical Research and Experimental Analysis on the Depth Measurement of Subsurface Damage

光学元件的亚表面损伤指的是在加工过程中产生的划痕和裂纹等。在激光的照射下,亚表面损伤会使光场发生变化,并且随着激光照射时间的增加,裂纹会越来越大,产生散射,最终影响光束的能量集中度。基于全内反射法测量亚表面损伤的原理提出了一种新的估计损伤深度的方法。入射光波和出射光波在样品表面下方叠加形成驻波,入射光的偏振态以及入射的角度会影响样品内部的光强分布。通过分析亚表面损伤点的光强度和入射角之间的关系,能够由入射角的改变量来估算亚表面损伤的深度。

The subsurface damage of optical components is the scratches and cracks which are produced in workpiece process. The subsurface damage will change the light field under the laser irradiation. As the laser irradiation time increases, the cracks become larger and generate scattering, which finally effect the encircled energy of laser beam. This paper proposes a new method to estimate damage depth based on the principle of subsurface damage measured by total internal reflection method. Incident and exit light waves are superimposed to form the standing wave under the surface of sample, and the polarization state and the incident angle of incident light affect the distribution of light intensity in the sample. By analyzing the relation between light intensity and incident angle of subsurface damage point, the depth of subsurface damage can be estimated through the change quantity of the incident angle.