一种大数值孔径小非球面检测用补偿器设计

利用补偿器的补偿法是检测高精度非球面的一种非常重要的方法,它可以利用已广泛实用的Zygo等高精度的数字干涉仪,用补偿法的关键是补偿器的设计.本文介绍了补偿法检测非球面的原理,针对要检测一种大数值孔径小非球面模芯,设计了一种由4片薄球面透镜组成的补偿器,该补偿器由前后两部分组成,前面两片组成一个数值孔径很小的系统,主要用于产生适量的球差,后组两片组成一个数值孔径较大的系统,并与前面的一起满足被测非球面检测的需要.文中对制造、检测及装调等主要误差源引起误差进行了全面分析.用这种补偿器检测相应的非球面,检测精度可达0.05λ,可满足光盘物镜非球面模芯的检测需要.

Null lens design for small aspherical surface with large NA

Compensation null test is a very important method in testing aspherical surface with high accuracy,in which a Zygo high accuracy digital interferometer is used. The design of a null lens is the key problem for compensation null test. In this paper, the principle of compensation null test is described. In connection with the being tested small aspherical mold surface with large NA, we developed a kind of null lens system made up of four thin lenses. The first two thin lenses form a system with very small NA mainly used to produce suitable spherical aberration; the other two form a large NA system, which together with that of the front two elements meets the null testing need. The wavefront variation of testing system due to the manufacture, test, assembly and adjustment errors is analyzed in detail. We are capable of measuring the aspherical surface to the accuracy of 0.05λ, which is enough to satisfy the testing of the mold surfaces of compact disc object lenses.