用校正法提高补偿器检测法的精度

Improving precision of null lens method with correction technique

研究了一种测量、分离补偿法检测补偿器非圆对称误差的技术,这种技术基于波面误差可用泽尼克圆多项式来表述。通过使补偿器或被测非球面绕系统光轴旋转到多个不同的角度,得到多个测量结果,根据这些测量结果,计算得到由补偿器误差带来的波面误差的非圆对称项泽尼克圆多项式系数,接着根据这些非圆对称项泽尼克圆多项式系数制作一个校正文件对非球面的测量结果进行校正,利用该技术可有效减轻对补偿器材料、加工及装校的苛刻要求,提高测量精度。实验结果表明:对某一被测非球面不用该技术时测量结果为0.105λ(RMS),应用此技术后的测量结果为0.026λ(RMS),且被测面在几个任意不同角度时的测量结果相差只有0.001λ(RMS),效果很好。该技术已被应用到实际的双曲面凸面反射镜的测量中。

Based on the wavefront aberration, a technique expressed by Zernike＇s circle polynomials was developed to test and separate the unsymmetrical error of null lens. By turning the null lens or the tested surface in different angles along their optic axis, the different testing results were obtained. According to these results, the wavefront aberration＇s unsymmetrical coefficients of Zernike＇s circle polynomials caused by the error of null lens were obtained, then a corrective file to correct the last testing result can be given. With this technique, the demands on the material, manufacturing, and assembly of null lens is not so critical, and the test accuracy is improved observably. The experimental results show, before and after the correction technique is used, the test result is 0. 105λ, and 0. 026λ, respectively, and the difference among four testing results of the mirror in four different orientations is less than 0. 001λ, so that the technique has been successfully applied to test a hyperboloid convex surface.