Absolute surface form measurement of large flat optics based on oblique incidence method

In this paper, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the matrix of transmission flatness and reference flatness. The new method can not only calibrate the reference flat error of large aperture interferometer, but also provide the absolute measurement method for large rectangular optical components applied in high power laser systems.