Analysis of second harmonic generation and deformation of a KDP crystal based on residual stresses of the supporting frame

The residual stress of KDP crystal supporting frame, deformation and stress of KDP crystal caused by the residual stress of crystal frame, as well as the influence rule of the second harmonic conversion efficiency were studied. On the basis of the analysis of the mechanism of grinding machining producing residual stress, through the calculation of power and thermal loads, a two-dimensional finite element model of grinding was established, and the internal and surface stress distribution in the grinding process and after cooling were obtained. The hole drilling method was used to test the surface residual stress of the crystal frame specimens. Based on the results of two-dimensional finite element method of grinding, the effect of residual stress relaxation on surface accuracy of crystal frame was calculated, and according to which a three-dimensional equivalent model and an integrated finite element model of the crystal holder assembly considering the influence of residual stress relaxation were established to calculate the residual stress-induced crystal deformation and stress-induced refractive index. On this basis, the phase match and the second harmonic conversion efficiency considering phase mismatch were obtained. The results showed that residual stress of different symbol and magnitude had diverse effects on the second harmonic conversion efficiency.