基于光热位移原理的KDP晶体光吸收系数干涉测量方法的数学模型及结构参数优化

Mathematical model and structure parameters optimization of KDP crystal optical absorption coefficient measurement with interferometry method based on photothermal displacement principle

KDP晶体的光吸收系数是评价其光学质量的重要参数。尤其在惯性约束核聚变装置(ICF)中,其大小直接决定出射脉冲的能量及频率转换效率,因此必须对它进行高精度测量。KDP晶体光吸收系数的数量级一般在10-3/cm^10-5/cm,传统的光吸收系数检测方法已经无法满足该测量分辨率要求。文中针对KDP晶体的特点提出了一种基于光热位移原理的干涉测量方法来解决其吸收系数精密测量的问题。首先利用积分变换思想建立了KDP晶体光吸收系数干涉测量数学模型,然后基于该模型对测量系统的结构参数进行了仿真优化,得到了系统的设计参数。

The optical absorption coefficient of KDP crystal is an important parameter to evaluate its quality. Especially, in the Inertial Confinement Fusion （ICF） facility, the amount of the optical absorption coefficient determines the energy and frequency conversion efficiency of output pulses directly. So it is need to measure it with extreme precision. Since the magnitude of optical absorption coefficient of the KDP crystal is generally 10-3/cm^10-5/cm, traditional detection methods cannot meet the measurement resolution requirement. In this paper, an interferometry method based on the photothermal displacement principle was proposed to solve the problem of measuring the optical absorption coefficient with extreme precision in connection with the characteristics of KDP crystal. The mathematical model within interferometry method of KDP crystal optical absorption coefficient was established by the integral transfer method firstly, then the structure parameters of the measuring system was simulated and optimized based on the above model, and the design parameters of the system were obtained.