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为了研究TEA CO2激光重复频率对远场光束特性的影响,首先采用有限元方法计算了不同重复频率下反射镜的温度场和热变形分布,然后采用协方差矩阵法对镜面热变形进行了Zernike拟合,最后结合衍射的角谱传播理论和功率谱反演法分析了不同重频TEA CO2激光经过内光路热畸变作用后的远场光束特性。研究表明:在净吸收能量相同的情况下,随着重复频率的增大,反射镜的温度逐渐升高,热变形量逐渐增大,经过内光路热畸变作用后,远场光束的Sr和平均能量密度Ed逐渐减小,β参数逐渐增大,光束质量逐渐变差;对于TEA CO2激光,重频为300 Hz的Ed值仅为10 Hz的40%,远场光束的峰值光强下降了43%,光斑展宽了近60%。文中的研究结果为TEA CO2激光发射系统的优化设计提供可靠的依据。
In order to study the influence of TEA CO2 laser repetition rate on the beam characteristics in the far field, the temperature field and the thermal deformation distribution of the mirror under different repetition frequencies were calculated by the finite element method first. Then the thermal deformation of mirror was simulated by Zernike In the end, the far-field beam characteristics of the TEA CO2 laser with different re-frequency TEA CO2 laser thermal distortion were analyzed combining the theory of angular spread spectrum and the power spectrum inversion. The results show that with the same net absorption energy, the temperature of the mirror gradually increases and the amount of thermal deformation increases with the increase of the repetition frequency. After the thermal distortion of the inner light path, the Sr and average The energy density Ed gradually decreases and the β parameter gradually increases, and the beam quality deteriorates gradually. For the TEA CO2 laser, the Ed value of 300 Hz is only 40% of 10 Hz, and the peak light intensity of the far-field beam is reduced by 43 %, Spot broadened nearly 60%. The research results in this paper provide a reliable basis for the optimal design of TEA CO2 laser emission system.