干涉法实时测量浅度非球面技术

提出了一种干涉实时检测非球面的新方法，该方法无需补偿器，CHG等辅助元件就能实现对浅度非球面的测量。对非球面度较小的非球面，直接利用标准球面镜作为参考表面，通过数字干涉仪可以测得全孔径位相分布，将所得的数据剔除参考球面波相对理论非球面的偏差，并运用最小二乘拟合求得机构定位误差，消去此误差，从而能够获得真实的面形信息。利用该方法对一口径为350mm的浅度双曲面进行了测量，通过数据分析和处理得到面形误差的PV值和RMS值分别为0.387λ 和 0.048λ ( =632.8nm)。并将该结果与零位补偿的检测结果相比较，两面形分布是一致的，其PV值和RMS值的偏差分别为0.033λ 和 0.006λ 。说明该技术对检测浅度非球面是切实可行的。

Testing of weak aspheric surfaces by real-time interferometry

A real-time interferometric method for testing asphere was proposed. It can measure aspherical surface of small asphericity without other null optics. When the tested asphere is close to a sphere，a sphere mirror is used as the reference surface. The phase distribution can be obtained by the the digital wavefront interferometer. The surface error was obtained by substracting the theory wavefront error from the phase datum and eliminating the translation error though least-squares fitting. Meanwhile the experiment was carried on with a 350mm aspheric mirror by this method. As results, the PV and RMS of the surface error was 0.387λ and 0.048λ , respectively; the surface map and interferogram were consistent to the surface map and interferogram tested by null compensation; and the difference of PV and RMS error between them was 0.033λ and 0.006λ , respectively. The results conclude that this method is feasible and accurate.