Laser feedback displacement measuring method and system based on external cavity modulation and frequency stabilization

Abstract

The invention relates to a laser feedback displacement measuring method and a system based on external cavity modulation and frequency stabilization. The method comprises the steps that piezoelectric ceramic is fixed on a measured target and laser output by a dual-frequency laser propagates towards a spectroscope and a feedback mirror along a laser axis; a driving circuit transmits a triangular wave voltage signal to the piezoelectric ceramic, the piezoelectric ceramic stretches out and draws back under the effect of voltage and pushes the feedback mirror to move back and forth at the same time; a minimum query unit is started up to search for a measuring reference point in each driving circle and a minimum to a displacement display for displaying; a frequency stabilization control circuit transmits a frequency stabilization signal to control a resistance wire to heat a laser gain tube, the cavity length of the dual-frequency laser is changed and the dual-frequency laser is enabled to be in a frequency stabilized state; before displacement is measured, zero clearing operation is conducted to the displacement display; a displacement measuring system starts to measure, and after the movement of the measured target is completed, a signal processing system transmits values to the minimum query unit and the value with driving voltage being zero within the driving cycle is searched and transmitted to the displacement display for displaying. The laser feedback displacement measuring method and the system based on the external cavity modulation and frequency stabilization can be widely used for displacement measurement.

Description

technical field [0001] The invention relates to a laser feedback displacement measurement method and system, in particular to a laser feedback displacement measurement method and system based on external cavity modulation frequency stabilization. Background technique [0002] The laser feedback displacement measuring instrument has the advantages of high sensitivity, self-collimation, simple structure and high cost performance, and has a wide range of applications in the fields of precision machining, vibration monitoring and imaging. The principle of the laser feedback displacement measuring instrument is the laser feedback self-mixing interference effect. After the laser is reflected from the surface of the measured target, it returns to the inside of the laser resonator again, and modulates the light field inside the laser to make the amplitude, phase and polarization state of the laser etc. change, and the motion information of the measured target can be obtained by demo...

AI Technical Summary

Problems solved by technology

Since the high-order feedback light is very sensitive to changes in the environment, small external vibrations will cause severe disturbances in the feedback light field, causing the internal light field of the laser to be modulated unevenly, causing changes in the light intensity of the laser or even polarization jumps, and polarization jumps It happens almost instantaneously. At this time, the frequency stabilization method of light intensity difference will not be able to stabilize the frequency of the laser feedback displacement measuring instrument.

In order to ensure that the laser feedback displacement measuring instrument can work stably for a long time, the existing technology often avoids high-order feedback during measurement, and uses methods such as light intensity attenuation to convert high-order feedback into weak feedback, and then performs measurement. However, at this time, the laser feedback The resolution of the displacement measuring instrument will be greatly reduced, which will affect its performance

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