强激光反射镜热畸变对光束传输特性的影响

Influence of thermal deformations of high power laser mirroron beam transfer characteristic

通过等效净吸收功率密度方法获取了强激光反射镜热畸变的干涉图像,提出了热畸变反射镜在平面波照射下近场波面畸变与远场光斑的计算方法,探讨了强激光远场光斑测试的一种新思路。定量分析结果表明,对单晶硅镜,在净吸收功率210W,光照时间为6s时,最大热畸变达到0.76μm,由此造成的近场波面Zernike离焦系数为0.32μm,x方向和y方向彗差分别为0.13μm和0.22μm,x方向倾斜系数上升到0.12μm,光束质量因子达5.7。

This paper presents a method of obtaining distorted wavefront and farfield spots generated by ideal beams from a mirror of laser induced deformations, through the calculating the interferograms of mirrors which are obtained by the experimental method of equivalent power density of pure absorption, and discusses a new idea of measuring farfield spot of high power laser. The results of quantitative analysis indicate that, for pure Si mirror, when the power of pure absorption is 210W and irradiating time is 6s, the maximum thermal deformation is 760nm,and because of deformations the defocusing of nearfield wavefront 320nm, primary coma along x axis and y axis is 130nm and 220nm respectively, the tilt along x axis is up to 120nm, and the beam quality factor is 5.7.