Analysis of spurious diffraction orders of computer-generated hologram in symmetric aspheric metrology

• DOI: 10.1364/oe.25.020556
• Publication Date: 2017-08-15T22:27:49Z
• Authors: Yiwei He; Xi Hou; Fan Wu; Xinxue Ma; Rongguang Liang
• Keywords: Spurious relationship; Distortion (music); Ptychography

Computer-generated hologram (CGH) has been widely used as a wavefront compensator in symmetric aspheric metrology. As diffractive element, it generates different diffraction orders, but only the 1st-order is to test surface. The light from spurious orders (SDO) will produce many high-frequency fringes interferogram and reduce measurement accuracy. In this paper, we regard CGH null system an imaging develop aberration model Seidel formalism analyze SDO. This advantage address difference between SDO (k1, k2) (k2, k1). We consider effect of pupil distortion so that our can with large distortion. derive condition ensure 2nd-order 4th-order aberrations have same sign calculate minimum defocused distance (power carrier frequency) CGH. According marginal-ray heights (h1andh3) on first second passes, determine covers whole pass. 4 designs compare results these real ray trace. These validate feasible whether part convex or concave inside outside focus transmission sphere.