基于立式Fizeau型干涉仪曲率半径测量系统,提出了一种简捷的离焦补偿算法,该算法对猫眼和共焦零位置的离焦量进行补偿,达到了提高曲率半径测精度的目的。从理论的角度分析了待测面波前像差中的离焦量与待测面位置偏移量之间的线性关系,并得到了两者之间变化的斜率。结果表明,猫眼和共焦零位置附近离焦量的大小与待测面位置偏移量之间为线性关系,且拟合直线的斜率与理论值相一致。同时,当待测面在共焦位置存在离焦时,利用离焦补偿算法使曲率半径测量精度提高了一个数量级。 Based on the vertical Fizeau interferometer curvature radius measurement system, a simple defocus compensation algorithm is proposed, which compensates for the defocus amount of the cat eye and the confocal zero position, and achieves the goal of improving the accuracy of curvature radius measurement. From the theoretical point of view, the linear relationship between the defocus amount in the wave front aberration of the test surface and the position offset of the test surface is analyzed, and the slope of the change between the two is obtained. The results show that there is a linear relationship between the amount of defocus and the offset of the measured surface near the cat’s eye and the confocal zero, and the slope of the fitting line is consistent with the theoretical value. At the same time, when the surface to be measured is out of focus in the confocal position, the accuracy of curvature radius measurement is improved by an order of magnitude by the defocus compensation algorithm.