Absolute testing of surface based on sub-aperture stitching interferometry

Abstract

Large-aperture optical elements are widely employed in high-power laser system, astronomy, and outer-space technology. Sub-aperture stitching is an effective way to extend the lateral and vertical dynamic range of a conventional interferometer. Most of the commercial available sub-aperture stitching interferometers measure the surface with a standard lens that produces a reference wavefront, and the precision of the interferometer is generally limited by the standard lens. The test accuracy can be achieved by removing the error of reference surface by the absolute testing method. In our paper we use the different sub-apertures as the different flats to get the profile of the reference lens. Only two lens in the testing process which is fewer than the traditional 3-flat method. In the testing equipment, we add a reflective lens and a lens which can transparent and reflect to get the non rationally symmetric errors of the testing flat. The arithmetic is present in this paper which uses the absolute testing method to improve the testing accuracy of the sub-aperture stitching interferometers by removing the errors caused by reference surface.