Homodyne one-dimensional grating displacement measurement device

Abstract

The invention provides a homodyne one-dimensional grating displacement measuring device, comprising a single-frequency laser, a polarization beam splitting prism, a beam splitting prism, a plane mirror group, a quarter wave plate, two signal receiving units and a signal processing system, wherein the single-frequency laser It is used to emit a beam of linearly polarized light with a fixed frequency, which is incident to the polarizing beam splitter prism for beam splitting, and a beam is reflected to the plane mirror group, which is vertically incident to the diffraction grating through the 1 / 4 wave plate, and diffracted by the diffraction grating to generate diffracted light, which is passed through the plane mirror group, The 1 / 4 wave plate and the polarizing beam splitting prism are incident on the beam splitting prism; the other beam is symmetrical with it to generate diffracted light, and the two diffracted beams interfere to form the interference light after being split by the beam splitting prism and enter the two signal receiving units respectively. The invention can not only realize the straightness measurement of large stroke, but also realize the displacement measurement of four times subdivision of single diffraction, and can realize the displacement measurement of eight times subdivision by using right angle prism or corner prism.

Description

technical field [0001] The invention relates to the technical field of ultra-precise displacement measurement, in particular to a homodyne one-dimensional grating displacement measurement device that realizes 4-fold optical subdivision based on single diffraction and can also form a traditional four-step phase-shift structure measurement. Background technique [0002] Grating displacement measurement systems are widely used in aerospace, semiconductor manufacturing, ultra-precision machining and other fields. With the rapid development of industrial technology, the measurement dimension, measurement speed, measurement accuracy, and measurement range of ultra-precision displacement measurement technology Increasingly demanding. The grating displacement measurement system uses the grating pitch as the measurement basis to eliminate the error caused by the change of laser wavelength. Because the grating displacement measurement system has low environmental requirements, low cos...

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Problems solved by technology

[0004] The traditional four-step phase-shift structure is mostly used in homodyne grating displacement measurement systems at home and abroad. One is used as a reference grating and the other is used as a measuring grating. The diffracted light generated by the reference grating and the diffracted light generated by the measuring grating are at the polarization beam splitter Interferometry, although the cost is reduced, but the volume of the grating measurement system is increased, and the measurement accuracy is limited

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