High-precision interference-type dual phase grating displacement sensor for surface topography measurement

Abstract

The invention discloses a high-precision interference-type dual phase grating displacement sensor for surface topography measurement, which comprises a laser, a reflection-type cylindrical holographic phase grating, two symmetrically-arranged plane reflectors, a reference plane grating with the linear density double that of the reflection-type cylindrical holographic phase grating, two symmetrically-arranged photodetectors, two signal processing devices connected with the two photodetectors respectively, a measurement lever with one end connected with the reflection-type cylindrical holographic phase grating, and a contact pin connected with the other end of the measurement lever and contacted with the surface of a to-be-measured workpiece. The reflection-type cylindrical holographic phase grating generates + / - 1-order diffraction light with a diffraction angle to be theta, the light is reflected by the two plane reflectors and is then incident to the same grating area on the reference plane grating, two groups of different-order diffraction light interference fringes are generated in + / -theta angle directions respectively, the interference fringes are received by the two photodetectors respectively and are converted to electric signals, and the electric signals are transmitted to the signal processing devices for being processed.

Description

technical field [0001] The invention relates to a high-precision interference type double-phase grating displacement sensor for surface topography measurement. Background technique [0002] In surface roughness measurement, the stylus method (also known as Taylor method), as a commonly used contact measurement method, is an internationally recognized standard method for two-dimensional surface topography measurement. The displacement conversion devices used in the stylus method include inductive, grating interferometric, Michelson interferometric, scanning white light interferometric, etc. Among them, the grating interferometric displacement measurement system based on the principle of grating diffraction interference can obtain large range and high resolution at the same time. The displacement measurement system is a very promising method for surface topography measurement. The grating interferometric displacement sensor currently used for surface topography measurement i...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to propose a high-precision interferometric dual-phase grating displacement sensor for surface topography measurement, to overcome the complex optical path, large structure, insufficient optical resolution and dual-plane grating mechanism of single-cylindrical grating interference displacement sensor. The complex structure and interference fringes have the disadvantages of reducing the signal quality due to the interference of other high-order diffracted light, and have the characteristics of high optical resolution, simple mechanical structure, small size, and high quality interference signal

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