终端靶场中相位畸变对近场光束质量的影响

Influence of Phase Distortion on Near Field Beam Quality in Final Target System

终端靶场聚焦系统中的光学元件上存在不可避免的缺陷致使光场波前发生畸变,根据高功率激光装置终端靶场系统中强光束传输的特点,建立了描述光学元件引入的局域相位调制的模型,研究了终端靶场中具有高斯型相位波前畸变的平顶光束经过透镜会聚,并在后续防溅射板等熔石英介质中经历非线性增长的传输演变过程,详细分析了高斯型相位波前畸变、熔石英厚度和透镜焦距对终端靶场聚焦系统中的近场光束质量的影响。结果表明,高斯型波前畸变越严重、熔石英厚度越长、透镜焦距越短,近场光束质量越差,中高频增长越多。

There are inevitable defects in optical elements of the final target system, which bring in wavefront distortion. According to the intense light beam propagation characteristics of the final target focusing system of high power laser, a model of localized phase distortion brought by optical elements is established. In final target system, a plane beam with Gaussian phase distortion is focused by the lens and then passes through fused silica, such as the subsequent splash-proof panels, in which nonlinear growth is experienced. The influences of Gaussian phase distortion, thickness of fused silica and focal length on the near field beam quality of the final target focusing system are investigated in detail. Results demonstrate that when the wavefront distortion is more serious, the thickness of fused silica is longer, and the focal length is shorter, the near field beam quality is worse and the growth of middle- high frequency component is bigger.