光学元件失调对光腔衰荡高反射率测量影响的理论分析

在利用光反馈光腔衰荡技术测量大口径光学元件反射率及其均匀性分布时,需要对光学元件进行二维扫描测量,而在扫描过程中光学元件的倾斜失调将对测量结果造成影响.本文根据失调谐振腔光束传输增广矩阵,通过数值运算模拟了在对称共焦腔和一般稳定腔情况下,光反馈衰荡腔结构中由样品倾斜失调引起的输出腔镜上光斑中心位置变化以及对反射率测量的影响.仿真结果表明:对称共焦腔情况下,输出腔镜上奇数次光斑无漂移,偶数次光斑漂移量为固定值|在一般稳定腔情况下,输出腔镜上奇偶数次光斑均往复振荡漂移.分析表明,该系统对样品失调角度的敏感程度与样品在腔内的位置以及腔长有关,通过改变样品在腔内位置,选择适当腔长以及包络拟合法可以减小样品失调对测量结果的影响.

Influence of Test Mirror′s Misalignment on High Reflectivity Measurement with Cavity Ring-down Technique

In the measurement of reflectivity and uniformity distribution of large-aperture optical component,using optical feedback cavity ring-down technique,2-dimensional scan is required.Angular misalignment of the test component,which is induced during the scanning process,will influence the measurement accuracy.Based on the augmented matrix of the misalignment of optical resonator,the position of the light spots on the output cavity mirror and the influence on the high reflectivity measurement were calculated in the condition of the symmetric confocal resonator and stable resonator.In the symmetric confocal resonator,there was no drift of the odd light spots,while the drift of the even light spots was a constant for one angular misalignment.In the stable resonator,the drift of the odd and even light spots were reciprocating swing.The results show that the influence of the angular misalignment on the high reflectivity measurement is related to the position of the component and the cavity length.The methods of reducing the influence of the angular misalignment of the component on the measurement results are also presented.