Absolute measurement method for spherical surface based on multi-feature matching and averaging method

Abstract

The invention discloses an absolute measurement method for a spherical surface based on multi-feature matching and an averaging method. According to the method, on the basis of results of interference measurement of a cat-eye position and a plurality of confocal positions, data is processed to directly obtain error information of a surface shape of an optical element of a detected spherical surface, wherein the error information has nothing to do with an error of a reference surface. Feature shapes of a plurality of feature marks arranged on an optical element surface of a detected spherical surface are formed in measurement data of confocal position; on the basis of the feature shapes, accurate control of a rotation angle and accurate data matching are carried out by the multi-feature matching. And then, an average processing is carried out on a plurality of calculation results of a three-position method, wherein the three-position method comprises a cat-eye position measurement, a cerain confocal position measurement of the optical element of the detected spherical surface and measurement of confocal position that is obtained by rotating 180 degrees around the certain confocal position, so that the accuracy of an absolute surface shape error of the optical element of the detected spherical surface. According to the invention, a complex adjusting structure and an auxiliary alignment device are not needed; meanwhile, the repetition of the adjustment of an optical path can be avoided. Moreover, good balance between convenience in practical operation and accuracy of an absolute measurement result is maintained. Therefore, the absolute measurement method has great application value.

Description

technical field [0001] The invention relates to an absolute measurement method of a spherical surface, which belongs to the technical field of advanced optical manufacturing and detection. Background technique [0002] Spherical optical elements are widely used in optical systems, and how to realize the detection of high-precision spherical optical element surface shape still has certain challenges. Fizeau-type phase-shifting interferometer is the mainstream equipment for surface shape detection. The basic principle of interferometry is that the test light carrying the surface shape error information of the optical element under test interferes with the reference light reflected back from the reference surface, and then the interferogram is processed to calculate the phase value reflecting the measurement error information. The reference surface is used as an ideal measurement "ruler" for relative measurement, so the surface shape detection accuracy of the interferometer is...

AI Technical Summary

Problems solved by technology

The main challenge of the three-position method and the five-position method is to use the "cat's eye" to measure the position, and the test wavefront will have an optical path reversal at this position, which will not meet the common optical path condition; in addition, the adjustment error of the cat's eye position will lead to errors in the data processing process. Coordinates match, resulting in inaccurate calculation results

The three-position method requires the use of a complex eight-dimensional adjustment mount to achieve correct confocal position measurement and adjustment; the five-position method uses the center of the measurement data as the reference point, and requires that the interference fringes do not change significantly during the rotation process, which is required in practice. It takes a lot of time to repeatedly adjust the optical path

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