Birefringent laser self-mixing Doppler velocity measurement method

Abstract

The invention discloses a birefringent laser self-mixing Doppler velocity measurement method, which is based on a self-mixing interference effect of a large-frequency-difference birefringent double-frequency He-Ne laser, and comprises the steps of firstly, detecting the same moving target by utilizing two orthogonal polarization laser modes generated by the laser, and generating self-mixing interference at the same time; if a user wants to obtain self-mixing interference signals of two orthogonal polarization laser modes, separately detecting the two modes at a detection end of the system by using a Wollaston polarization splitting prism, carrying out independent detection by using two photoelectric detectors to obtain Doppler frequency shift mixing signals, extracting difference frequencyitems in the mixing signals, and finally, calculating the actual movement speed of a target by utilizing the linear relation between Doppler frequency shift and speed. According to the invention, themeasurable range of the self-mixing interference speed measurement technology is effectively expanded, and the optical carrier microwave frequency mainly depends on a birefringent crystal element ofthe laser cavity, so that the stability is very high, and the speed measurement precision is remarkably improved.

Description

technical field [0001] The invention belongs to the technical field of laser measurement, and in particular relates to a birefringence laser self-mixing Doppler velocity measurement method. Background technique [0002] In recent decades, thanks to scholars' in-depth research on the dynamic characteristics of the laser self-mixing interference effect, the Doppler velocimetry technology based on the principle of laser self-mixing interference has been developed quite maturely. Compared with the traditional laser Doppler velocimeter, the Doppler velocimeter based on the principle of laser self-mixing interference not only has similar phase sensitivity and modulation depth, but also has many advantages such as self-calibration and compact optical structure. In addition, when the laser works in a moderate optical feedback state, the self-mixing laser Doppler velocimeter can also intuitively distinguish the direction of the measured velocity by determining the inclination of the ...

AI Technical Summary

Problems solved by technology

However, the optical injection semiconductor laser system contains a variety of polarization optical components and electronic instruments involved in the generation of light-borne microwaves, such as polarizers, isolators, wave plates, microwave frequency synthesizers and avalanche photodetectors, etc., which undoubtedly makes the system The composition becomes very complex and expensive

For the self-mixing laser Doppler velocimeter, its own advantages are simple structure and low cost, while the light-borne microwave generator based on the optical injection semiconductor laser system will introduce a high-cost and complex structure, which makes Weakening advantages of self-mixing laser Doppler velocimetry

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