相干调制成像技术测量高重复频率激光器光学元件热畸变

Measurement of Thermal Distortion of the Optical Element in High Repetition Rate Laser with Coherent Modulation Imaging

高功率固体激光器工作在高重复频率时,增益介质因热量的沉积而发生热畸变,导致激光输出波前发生变化。为此,利用相干调制成像技术通过记录单幅衍射光斑实现输出光场的波前测量,获得了放大器工作在1,5,7Hz频率时光学元件的热畸变相位。实验结果显示,随着工作频率增大,热量向中心区域集中,热沉积效应明显增加了波前变化。

When high-power solid laser working in high repetition rate, the laser output wave-front changes due to the thermal distortion, which is caused by the gain medium under the heat deposition. Therefore, the coherent modulation imaging technology is used to realize the measurement of the laser output wave-front from one frame of diffraction intensity recorded. The phases of thermal distortion of the optical element are obtained when the amplifier working in 1, 5, 7 Hz frequency. Experimental results show that thermal distortion effect is significantly increased, the heat is concentrated toward the center region and the phase change increases as the working frequency increases.