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Phase modulation type orthogonal polarization laser feedback grating interferometer and its measurement method

A technology of orthogonal polarization and phase modulation, which is applied in the direction of measuring devices, instruments, and optical devices, etc., can solve the problems of complex optical path system, deviation between detection light and photodetector, difficult adjustment, etc., and achieve high modulation accuracy and wide modulation bandwidth The effect of widening and simplifying the structure

Active Publication Date: 2020-04-21
NANJING NORMAL UNIVERSITY
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Problems solved by technology

However, such systems generally face two problems: when the target moves a certain distance in an out-of-plane direction, the optical path of these systems will also change, resulting in a deviation between the detection light and the photodetector
Therefore, the measurement of out-of-plane displacement is usually used to compensate the in-plane displacement measurement; and these optical path systems are often very complicated and difficult to adjust

Method used

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  • Phase modulation type orthogonal polarization laser feedback grating interferometer and its measurement method
  • Phase modulation type orthogonal polarization laser feedback grating interferometer and its measurement method
  • Phase modulation type orthogonal polarization laser feedback grating interferometer and its measurement method

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[0030] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

[0031] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as herein Explanation.

[0032] Laser feedback interferometry technology is a new type of interferometry technology with high application value that has emerged in recent years. When the laser output light is reflected or scattered by external objects, part of the light will return to the laser resonator cavity and mix w...

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Abstract

The invention relates to a cross-polarization laser feedback grating interferometer of a phase modulation type, and a measurement method thereof. The measurement principle is based on the grating diffraction, optical Doppler effect, Lamb semi-classical theory and time-domain orthogonal demodulation principle. The orthogonally polarized light outputted by a birefringent dual-frequency helium-neon laser is perpendicularly incident to a polarization beam splitting prism and is divided into two linearly polarized light beams in different polarization directions. The two polarized light beams respectively pass through two different electrooptical modulators and then are respectively reflected by a reflector at a + / -1-order Littrow incidence angle to a reflection-type diffraction grating. The diffracted light returns to the laser cavity along the respective incident light, and performs self-mixing interference with the light in the cavity. The backward output light of the laser passes through a polarizer and then only the single-mode light is retained and accepted by a photodetector. An output signal of the photodetector is outputted to a data processing module for data processing, and the two-dimensional displacement of a target to be measured is obtained. The grating interferometer has the advantages of simple structure, large measuring range and high measurement resolution.

Description

technical field [0001] The invention belongs to the technical field of precision displacement measurement, and in particular relates to a phase modulation type orthogonal polarization laser feedback grating interferometer for two-dimensional measurement and a measurement method thereof. Background technique [0002] Nano-measurement is the key technology for the development of advanced manufacturing industry, and also the forerunner and foundation of the entire field of nano-technology. With the development of ultra-precision machining and ultra-fine machining technology, the demand for real-time high-precision two-dimensional positioning system is growing rapidly. Laser interferometer and grating interferometer are widely used in high-precision displacement measurement due to their advantages of non-contact, high resolution and wide dynamic measurement range. Typically, laser interferometry is used to measure out-of-plane displacements, while grating interferometry is used...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/02G01B9/02
CPCG01B9/02055G01B11/02
Inventor 郭冬梅施立恒孔令雯王鸣
Owner NANJING NORMAL UNIVERSITY
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