透过检测中的准直镜精度容限

在干涉检验过程中, 被检元件的面形误差检测精度受到干涉仪系统结构的影响, 从而降低测量结果的可靠性。为了得到较高的检测精度, 必须对检测系统进行分析, 建立测量误差和系统结构的关联度。根据菲涅耳衍射近似理论, 就菲佐干涉仪中的准直镜和标准镜面形误差对透过检测的影响进行了研究。通过对波前相位传递情况的分析, 得出波前误差和系统结构参量的相关性, 去除空腔系统误差, 优化结构参量, 并建立准直镜误差容限表达式。经计算得出, 当被检面形变误差为0.2λ时, 测试误差可以达到0.02λ, 而对准直镜的面形误差要求

During the optical interference testing, the measurement accuracy of the tested surface is influenced by the system structure of interferometer, which will decrease the reliability of the measurement. To obtain high measurement precision, it is necessary to analyze the testing system and build the relationship between the measurement error and system structures. With the Fresnel diffraction approximation method, the influences of the collimated lens and standard lens surface errors on the transparence testing are analyzed in Fizeau interferometer. Through analyzing the propagation of the wavefront phase, we obtain the correlation between the wavefront error and system structure parameters, remove the empty system error, optimize the structure parameter, and build up the expression about the tolerance limit of the collimated lens. We draw the conclusion that when the aberration of the tested surface is 0.2λ, the measurement error can reach 0.02λ, and the aberration of the collimated lens 0.8λ will be enough.