High-optical-subdivision grating interferometer based on plane mirrors

Abstract

A high-optical-subdivision grating interferometer based on plane mirrors comprises a double-frequency orthogonal linear polarization laser light source, a polarization beam splitter, the first mirror, the second mirror, the third mirror, the fourth mirror, a first quarter wave plate, a second quarter wave plate, a scale grating, a data collection, processing and control unit and a double-frequency heterodyne interference photoelectric detection unit which is composed of a non-polarization beam splitter, a first analyzer placed on the orthogonal double-frequency linearly polarized light by 45 degrees, a first detector corresponding to the first analyzer, a second analyzer placed on the orthogonal double-frequency linearly polarized light by 45 degrees and a second detector corresponding to the second analyzer. The scale grating is designed into a high-density -1-level sub-high diffraction efficiency reflection type grating, measurement light beams are diffracted multiple times through the scale grating through the combination with the plane mirrors, and therefore the high optical subdivision fold can be obtained, and important application value in the field of increasing the grating interferometer resolution ratio and accuracy is achieved.

Description

technical field [0001] The invention belongs to a high-precision displacement measuring device, in particular to a high optical subdivision grating interferometer based on a plane mirror. Background technique [0002] There are currently two main types of instruments for micro-nano precision displacement measurement: laser interferometer and grating interferometer. Laser interferometer is based on wavelength and can obtain high resolution, but its application is limited because the wavelength is easily affected by factors such as environment and light source. The grating interferometer just makes up for the shortcomings of the laser interferometer. It uses the grating period as the reference, and the measurement results are basically not affected by the environment and wavelength. It has been widely used in processing machine tools, robots, biomedical and other fields. [0003] Whether it is a laser interferometer or a grating interferometer, its resolution depends on the o...

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Problems solved by technology

[0004] Aiming at the problem of low optical subdivision multiples of the current grating interferometer, the present invention proposes a high optical subdivision grating interferometer based on a plane mirror, and designs a high-density scale grating with a negative first-order high diffraction efficiency, and then uses a flat mirror to realize The measuring beam hits the scale grating multiple times, so that the measuring beam is diffracted by the scale grating multiple times, thus obtaining a high optical subdivision multiple

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