大口径元件反射率的镜面扫描精密测量系统

Precise measurement system for reflectivity scanning of large aperture components

为了测量高功率激光传输系统中大口径高反射率元件,研制了一种镜面扫描的精密测量系统。介绍了该系统的结构及其工作原理,分析了影响系统测量精度的因素,理论上估算的测量精度为2×10-5。在直腔下对该系统的性能进行了实验测试,分析表明,系统的测量不确定度优于2.052 28×10-5,最大测量误差为3.554 04×10-5,与理论预计结果吻合较好。对大口径元件进行的多次实验扫描测试,结果显示,镀膜加工误差导致反射率分布是关于镜面中心呈旋转对称。该系统的使用大大简化了元件表面反射率分布的测量。

A precise measurement system of high reflectivity for scanning large aperture components in high power laser system is developed. The structure and working principle of this system are introduced, and those factors that influence its metrical precision are analyzed. According to theoretic analysis, precision of this measurement system is 2×10^-5. Experimental measurements for capability of this system were carried out, which show that RMS of measurement in linear cavity is better than 2. 05228×10^-5. Results give that the biggest measurement error is 3.55404×10^-5, which is in good agreement with the analysis. Scanning experimental measurements for large aperture components were also carried out. Results show that distribution of reflectivity is circular symmetric about the center of mirrors, which is caused by machining error in the course of film plating. The reflectivity measurement system makes it very easy to measure reflectivity distribution on large aperture components.