Study On The Total Internal Reflection Coarse Positioning System In Sub - Surface Damage Measurement Technique

The existence of subsurface damage increases the material removal of the optical components, and directly reduces its service life, long-term stability, coating quality, image quality and laser damage threshold and other important performance. The development of the energy, military, aerospace and other advanced research fields are largely restricted. Therefore, the control of the surface damage for the optical element has become a crucial technology in related fields. With the improving of the energy, people pay increasingly attention to the control of subsurface crack especially in the field of high-power laser.Firstly, it is a work that which can obtain a measurement method for the subsurface damage of optical elements based on the total internal reflection and the principle of polarized scattering. It analyzes the effects of the polarization state and the incident angle of the illumination light source on the dipole scattering of the defect of the surface and subsurface in the paper. The relationships of the parameters have been simulated by MTLAB. Secondly, the design parameters of the key components for the total internal reflection can be obtained through the formula derivation and simulation. It is mainly the design of the two parts. The first one is the design of light source optical system; the others are the design of the Wollaston prism and the Nomarski prism which are the elements of microscopic imaging system. Then the relation among the wedge angle, thickness and other parameters of Wollaston prism were determined; it also simulates the relation among the optical axis angle, wedge angle, thickness and the coherent plane of Nomarski prism. Finally, all components will be assembled, and the conditions of surface and subsurface will be observed.