为实现对凹非球面的高精度检测,提出并设计了一种二元纯相位型双计算全息图。设计的双计算全息图由主全息和对准全息两部分组成,分别用于检测非球面和精确定位主全息。介绍了双计算全息图的工作原理及其设计方法,并给出了一个检测Φ140、F/2抛物面反射镜的双计算全息图设计实例,实验得到的均方根(RMS)误差为0.062λ。通过分析对准全息的误差,推导出主全息的条纹位置畸变误差,最后计算出其综合误差为0.06λ。为验证实验结果的可靠性,将其与平面镜自准直检测结果(ERMS=0.062λ)比较,结果二者吻合良好。

In order to test concave aspherical surfaces precisely, a binary phase twin computer-generated hologram (CGH) is proposed and designed. The designed twin CGH consists of two segments, called main CGH and alignment CGH, used for testing aspherical surfaces and aligning main CGH respectively. The principle of testing aspherical surfaces is reviewed and the design method is introduced. Then a design example for testing a paraboloidal mirror (Φ140, F/2) is presented, and its root-mean-square (RMS) error is 0.062λ. The pattern distortion error of main CGH is derived from analyzing the errors of alignment CGH, and then the integrative error is 0.06λ. The validity of the test result is demonstrated and compared with that of autocollimation test, which is 0.062λ (RMS). It is demonstrated that the results show a good agreement.