High-spatial-discrimination long-range facial-form detecting device and method

Abstract

The invention discloses a high-spatial-discrimination long-range facial-form detecting device and method. The device comprises a scanning optical head and is characterized in that the scanning optical head comprises a small hole array plate, a beam splitter, a lens array and an array detector, the small hole array plate divides input parallel light beams into a plurality of parallel thin light beams, then the light beams enter the beam splitter, each thin light beam is input to the lens array in a transmission mode through the beam splitter, lens units in the lens array focus the corresponding thin light beams to the surface of an object to be tested respectively, and the light beams reflected by the surface of the object to be tested enter the array detector through the lens array and the beam splitter in sequence. The device is simple in structure and stable in performance, high-space-frequency sampling measuring can be carried out on the surface to be tested, measuring of facial-form errors of high frequency (larger than 1 line / mm) can be expanded, and at least 10 lines / mm can be achieved commonly.

Description

technical field [0001] The invention relates to the surface shape detection of large-scale mirror objects, in particular to a high-spatial resolution long-range surface shape detection system based on shear measurement. Background technique [0002] The surface error of the optical element surface has a very important impact on the performance of the optical system. According to the distribution of the spatial frequency of the surface error, it can be divided into high spatial frequency, medium spatial frequency and low spatial frequency error. The existing research results show that different frequency errors have different effects on the imaging system. For example, the refraction effect of high-frequency errors and the scattering effect of low-frequency errors will not significantly change the shape of the point spread function on the image plane, but will only cause the focus energy to change. Divergence, reduction of imaged contrast and signal-to-noise ratio, in contras...

AI Technical Summary

Problems solved by technology

However, the following two problems generally exist: (1) Since LTP uses a collimated beam to scan the sample, limited by the size of the scanning beam, the spatial frequency of the sampling point is relatively low (up to 1 line per millimeter (line per millimeter)), Obviously, some high-frequency surface shape error information cannot be effectively measured at present; (2) During the scanning process of the optical head, there are rotation errors of the air-bearing transmission table and laser pointing errors, although the reference optical path corresponding to the external mirror in LTP These errors can be partially eliminated, but because the reference optical path is slender, it is greatly affected by air disturbance, which reduces the accuracy of reference optical path correction

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