两种利用计算全息检测非球面的方法

Two Methods for Optical Testing Aspherical Surface by Using a Computer-generated Hologram

计算全息检测非球面具有广泛的应用潜力。但在一般情况下,检测的非球面波差范围是有限的。本文提供和验证了两种扩大计算全息检测能力的方法,其一是计算全息和零位光学系统组合补偿的检测法;其二是象差平衡法制作计算全息图的检测法。此两法把检测非球面波差范围扩大几倍直至近百个λ的波差。所用的线型计算全息图能方便地再现位相型波面。实验证实了这两种方法是可行的。精度分析表明,检测非球面面形偏差时,精度可达λ/10。

Applying a computer-generated hologram (CGH) in measuring anoptical wavefront is the new development in interferometry, particularly there isa situation with greart potentialities in the field of measuring optical asphericalsurfaces. As a general rule, the range of wave aberration to be measured by aCGH is limited. It affects the method to be widely used. In this paper, two methodsfor extending the capability of a CGH are discussed and investigated. One is thedefocussing method, while the other is a combination of CGH with a null opticalsystem. CGH is calculated and designed from rays tracing of the whole system. Soall the aberrations on optical components of the system have been taken intoconsideration. By using these two methods, the measured range of wave aberrationhas been extended nearly three times up to 100λ of wave aberration. Inter-ferometric computer-generated holograms are used in both cases. Experimental resultsproved these kinds of technique are available in practical work. From the erroranalysis, a precision of λ /10 can be obtained in measuring aspheric surfaces.