New technique for testing large optical flat

TLDR: This paper discusses the development of a new technique for testing larger optical flat only by means of a smaller interferometer, an overlapping subaperture interference testing (OSIT) technique, which has established a mathematics model for OSIT to retrieve the surface of the full aperture.

Abstract: This paper discusses the development of a new technique (including theory, method, and equipment, etc.) for testing larger optical flat only by means of a smaller interferometer. It is an overlapping subaperture interference testing (OSIT) technique. The author has established a mathematics model for OSIT to retrieve the surface of the full aperture. The theoretical accuracy of the retrieved surface of the full aperture reached (lambda) /200 (p-v). The relationship between the accuracy of the retrieved wavefront of full aperture and errors (such as system error of interferometer or position error of subapertures, etc.) has been investigated. A computer program was established to simulate the real procedure from testing surface data of subaperture to retrieved wavefront of full aperture.