非均匀激光辐照下硅镜热变形对光束传输特性的影响  

Effects of thermal distortion of Si mirror irradiated by non-uniformity laser intensity on laser propagation

作　　者：刘文广[1] 饶鹏[1] 华卫红[1] 

机构地区：[1]国防科学技术大学光电科学与工程学院,长沙410073

出　　处：《强激光与粒子束》2008年第10期1615-1619,共5页High Power Laser and Particle Beams

基　　金：国家高技术发展计划项目

摘　　要：使用有限元法计算了硅镜在DF化学激光器非稳腔输出的中空非均匀激光辐照下镜面温升和反射面面形随时间变化的特性,使用65阶Zernike多项式对镜面面形进行了曲面拟合,使用光线追迹的方法计算了平行光束经不同数量硅镜反射后的光束波前分布PV值、Strehl比和Zernike像差系数随时间变化的特性。计算结果表明:在典型的DF激光器输出的中空方形光束辐照下,硅反射镜的热变形将使反射光束产生波前畸变,波前畸变中,y方向像散项占据主要地位,其次是离焦项;随着激光系统中反射镜面数量的增加,高阶像差系数将逐渐增大,且波前PV值与反射次数成线性关系。The temperature distributions and thermal distortions of Si mirror non-uniformly heated by high energy laser beam are calculated with finite element methods, and the distorted mirror surface is fitted with 65 orders Zernike polynomials for the convenience of ray tracing. The wavefront changes over time with different times of reflection by 45° mirrors are presented, and the corresponding wavefront characteristics such as PV, Strehl ratio and aberration coefficients are tabled. The results show that, distortion occurred on Si mirror non-uniformly heated by the rectangular laser beam with rectangular port, and wavefront aberrations are introduced after multi-reflection. In the aberrations, the .y-astigmatism and defocus are main contributors. The high order aberration coefficients will grow large when the reflecting times increase, and wavefront PV value is nearly linear to the reflecting times.

关 键 词：激光辐照 高能激光 硅镜 热变形 光束质量 

分 类 号：TN248[电子电信—物理电子学]