Coaxial Fizeau synchronous phase shifting interferometer capable of adjusting extended light illumination

Abstract

The invention relates to a coaxial Fizeau synchronous phase shifting interferometer capable of adjusting extended light illumination and belongs to the field of an optical interference measuring device. The coaxial Fizeau synchronous phase shifting interferometer comprises an extended light source assembly, a fronting Michelson type interferometer assembly and a Fizeau main interferometer. In the invention, the fronting interferometer assembly is adopted to generate two illumination light waves of orthogonal polarization state; polarization phase shifting interferometry between a measured surface and a reference surface is realized through match of spatial coherence of the fronting interferometer and the main interferometer; and an additional fringe is removed by using the characteristic of a short coherent optical length of an extended light source space. The coaxial Fizeau synchronous phase shifting interferometer has the characteristics of long measuring distance, continuous and adjustable contrast ratio, continuous and adjustable coherent optical length, easy operation, lower error requirement on a high frequency surface shape of the reference surface and the like; and the coaxial Fizeau synchronous phase shifting interferometer can be used in the fields of high precision detection of an optical element, optical element on-line detection and super-smooth surface detection and the like.

Description

Technical field: [0001] The invention belongs to optical interference measuring instruments, in particular to a Fizeau type synchronous phase-shifting interferometer. Background technique: [0002] The Fizeau interferometer adopts the common optical path design of the measured beam and the reference beam. Except for the reference surface, the aberration of the interferometer optical system itself has basically the same influence on the measured beam and the reference beam, and most of them can cancel each other out. Fizeau-type interferometers only have high requirements on the accuracy of the reference surface, but have lower requirements on the processing and assembly accuracy of the system wave aberration and other components. Compared with non-common optical path interferometers such as Tieman Green type, the design and processing difficulty of Fizeau type interferometer is significantly reduced, so it becomes the first choice for wave aberration / surface detection of lar...

AI Technical Summary

Problems solved by technology

Since the time coherence matching between the pre-interference component and the main interferometer needs to realize the absolute compensation of the optical path difference, the moving range of the adjustable reflector in the front auxiliary component should be equal to the distance from the reference mirror to the measured mirror, which makes the front The range of movement of the adjustable mirror in the auxiliary component is very large, resulting in a bulky instrument structure that is difficult to miniaturize

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