Null compensation test with zero-power corrector

The null compensation-test method with zero power corrector for concave aspheric mirrors with deep relative aperture and wide clear aperture, including oblate ellipsoids which are very difficult to be tested, is investigated in detail. Based on the third-order aberration theory, both two-lens zero-power corrector and the three-lens zero-power corrector are introduced. This method is simple and free of chromatic aberrations. As for wide clear aperture and deep relative aperture concave aspheric mirrors, it is difficult to use a two-lens zero power corrector to do compensation test, so a three-lens zero-power corrector is used instead to solve the problem well. The design method of the corrector and specific design examples with clear apertures 800mm and relative apertures 1/2, 1/3, 1/4 of paraboloids are given and their design results are analyzed and compared.