High-resolution grating interferometer based on high-density gratings

Abstract

A high-resolution grating interferometer based on high-density gratings comprises a linear polarization light source, a polarization beam splitter, a first reflector, a second reflector, a third reflector, a fourth reflector, a first quarter wave plate, a second quarter wave plate, a data acquisition, processing and control unit, a double-frequency heterodyne interference photoelectric detection unit and an auto-collimation device, wherein the double-frequency heterodyne interference photoelectric detection unit is composed of a non-polarization beam splitter, a first polarization analyzer placed on orthogonal double-frequency linearly polarized light by 45 degrees, a first detector corresponding to the first polarization analyzer, a second polarization analyzer placed on the orthogonal double-frequency linearly polarized light by 45 degrees and a second detector corresponding to the second polarization analyzer. The high-density gratings are designed to have negative first-class high diffraction efficiency. Thus, subdivided gratings are adopted, so that light beams are diffracted by a scale grating many times and finally are vertically reflected to the reflectors, and light paths return by the way that light paths come; the light beams are diffracted by the scale grating many times, so that a high optical subdivision multiple is obtained, and the resolution of the grating interferometer is improved.

Description

technical field [0001] The invention relates to a high-resolution component of a grating interferometer in a displacement measuring device, in particular to a high-resolution grating interferometer based on a high-density grating. 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 inte...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem of low optical subdivision multiples of current grating interferometers, the present invention proposes a high-resolution grating interferometer based on high-density gratings. The subdivision grating realizes multiple repeated diffractions of the light beam between the two gratings, and finally vertically incident on the mirror to realize the return of the original path of the light path. The beam is diffracted by the scale grating many times to obtain a high optical subdivision multiple, thereby Improving the Resolution of Grating Interferometers

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