Study On Sub - Surface Damage Depth Location Based On Total Internal Reflection Method

The subsurface damage of optical component seriously affect the anti-laser damage threshold of optical system, the image quality of large optical system, and directly reduces its service life, long-term stability, coating quality and long-term stability of the system. The development of the energy, military, aerospace and other advanced research fields is largely restricted. Therefore, the control of the surface damage has become a crucial technology in optical fields. But people pay rarely attention to the subsurface damage issues in traditional optical. With the improving of the laser energy, more and more attention is paid to the controlling of subsurface damage only in the field of high-power laser system.In this paper, a method of measuring the subsurface damage depth position is studied, which is based on the principle of total internal reflection. According to basic principle of the total internal reflection method, it analyzes the relationship between the visibility of subsurface damage points at different depths position and the angle of incidence by the standing wave formed in the internal sample, and by changing the angle of incidence to estimate the depth of subsurface damage. In order to enhance the visibility of subsurface damage defect, the differential interference system is added. Then the relation among the wedge angle, thickness and other parameters of Nomarski prism are determined. Finally, all components will be assembled. By comparing the different subsurface damage images, it verified the feasibility of measuring subsurface damage depth position based on total internal reflection.