System and method for accurately calibrating optical path of point diffraction interferometer based on image information

Abstract

The invention discloses a system and a method for accurately calibrating an optical path of a point diffraction interferometer based on image information. The system comprises spectroscopic prisms, abeam expanding collimation system, a diffraction orifice plate, a wave-front sensor, lenses, an optical power meter, three-dimensional precision electronically controlled translation stage and driverthereof, a CCD1 (charge-coupled device), and a computer. The method comprises the following steps of: analyzing and obtaining a mathematical relationship between an alignment error and a diffraction wave-front deviation by using the Rayleigh-Sommerfeld diffraction theory; designing an accurate optical path calibration system according to requirements to obtain a spot-hole alignment image and lightintensity before and after the diffraction orifice plate; then analyzing and measuring alignment deviation information through an image processing algorithm to establish a mathematical model betweenthe measurement quantity and the control quantity; and finally, achieving accurate calibration according to a system implementation principle. According to the system and the method for accurately calibrating the optical path of the point diffraction interferometer based on the image information, the precise alignment of the diffraction holes and the spot in the visual environment is realized, andthe influence of the alignment deviation on the detection precision of the point diffraction interferometer to some extent is eliminated. The system and the method have characteristics of high precision and high efficiency, and reduce the damage of the laser to the vision of operators during experimental operation.

Description

technical field [0001] The invention belongs to the technical field of laser interference precision measurement, in particular to a system and method for precisely calibrating the optical path of a point diffraction interferometer based on image information. Background technique [0002] With the development of science and technology, high-precision optical components and optical systems are widely used in precision lithography (EUVL), aerospace, military weapons, high-end civilian equipment and other fields, and their manufacturing accuracy affects the performance of the instrument. Interferometry is an important method for measuring the surface shape of optical components, which is usually used in the fine polishing stage in the later stage of processing. The current mainstream interferometers include Fizeau type and Tieman-Green type interferometers, and their detection accuracy RMS is about λ / 60~λ / 100 (λ=632.8nm), PV<λ / 20 level. Limited by the precision of the standa...

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Problems solved by technology

This method has low calibration efficiency and poor accuracy, and long-term operation will cause great damage to vision

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