Annular sub-aperture stitching used for aspheric testing

In order to solve the problem of high-precision measurement of aspheric mirror,we put forward the method of aspheric annular sub-aperture stitching testing by using Zygo interferometer.By moving the stay of the testing aspheric surface,the reference spherical waves produced by the inteferometer could match the different band areas of the testing aspheric surface with different curvature radii, each annulus was tested,then the whole aspheric surface testing could be completed.A hyperboloid reflector was tested with annular sub-aperture stitching, and a light path was set up to verify the stitching result using aberrationfree point method . The results show that the error is less than 1/20 (=632.8 nm).