Methods of testing of optical parameters of large-sized mirrors off-axial surfaces at the stage of figuring and certification

JSC LZOS has been using diffraction optical elements (DOE) or Computer Generated Holograms (CGH) for many years to test the surfaces of large-sized optical mirrors for astronomical and space purposes. They are used for aspherical surface figure testing; testing of aspherical surface vertex position relative to the mirror geometric center, calculation of distortion in interferogram image, mutual adjustment of mirrors in testing scheme, etc. Thus, CGH have become an integral part of the up-to-date testing of large-sized optical mirrors and optical systems aspherical surfaces.