Ichioka Y, Lohmann A W
Appl Opt. 1972 Nov 1;11(11):2597-602. doi: 10.1364/AO.11.002597.
In testing a large aspheric mirror such as a paraboloid, one uses as interferometric reference a small spherical mirror together with a test glass. The combination of mirror and test glass produces a parabolic wavefront for comparison. Recently holograms have been used as synthetic test glasses. The average fringe distance of the grating-like holograms has to be fine enough if separation of the diffraction orders is required. We propose to use holograms with circular fringes. Now the different diffraction orders come to focus at different locations on the optical axis, where all but one order can be eliminated. This is easily possible, since the waves coming from a mirror with a central hole are hollow cones. Several ways for making these computer-generated circular holograms are suggested.
在测试大型非球面镜（如抛物面镜）时，人们会使用一个小的球面镜和一块测试玻璃作为干涉测量的参考。镜子和测试玻璃的组合会产生一个抛物面波前用于比较。最近，全息图已被用作合成测试玻璃。如果需要分离衍射级次，类光栅全息图的平均条纹间距必须足够精细。我们建议使用具有圆形条纹的全息图。现在，不同的衍射级次会在光轴上的不同位置聚焦，除了一个级次之外，其他级次都可以被消除。这很容易实现，因为来自带有中心孔的镜子的波是空心圆锥。文中还提出了几种制作这些计算机生成的圆形全息图的方法。
