A dual-wavelength ld self-mixing vibration measuring instrument with adjustable resolution and its measuring method

Abstract

The invention provides a dual-wavelength LD self-mixing vibration measuring instrument with adjustable resolution, and the measuring instrument comprises a dual-wavelength LD for emitting laser, an optical path adjustment device, a light density filter, a to-be-detected target, a drive power supply in electrical connection with the dual-wavelength LD, a signal processing device and a data collection and analysis device, wherein the optical path adjustment device, the light density filter and the to-be-detected target are sequentially set along a transmitting optical path, and the signal processing device and the data collection and analysis device are sequentially in communication connection with the dual-wavelength LD. The invention also provides a measurement method of the measuring instrument, and the laser with the dual wavelengths outputted by the dual-wavelength LD passes through the optical path adjustment device and the light density filter to reach the to-be-detected target. The laser is reflected by the to-be-detected target and then returns to the respective resonant tube cavities to perform the self-mixing interference with the light in the resonant tube cavities. A computer carries out the analysis processing of the self-mixing signal transmitted through communication via an even equivalent wavelength Fourier transform algorithm, thereby achieving the adjustable-resolution target vibration measurement.

Description

technical field [0001] The invention provides a technical field of precision optical interferometry, more specifically, a dual-wavelength LD self-mixing vibration measuring instrument with adjustable resolution and a measuring method thereof. Background technique [0002] Vibration measurement is an important branch of metrology. In many fields such as scientific research, industrial production and medicine, it is necessary to measure the vibration of the target. In advanced manufacturing fields such as precision machinery and micro-electromechanical systems, vibration measuring instruments generally require small space, high sensitivity, and non-contact measurement; there is an urgent need for vibration sensors with adjustable resolution to meet the needs of different working conditions . [0003] Traditional vibration measurement methods mainly include potentiometer type, inductive type, eddy current type, capacitive type, magnetostrictive type, etc., but the technical pe...

AI Technical Summary

Problems solved by technology

However, the existing methods need to know the relevant parameters of the target, which greatly limits the application of this technology in actual measurement, resulting in the use of half-wavelength fringe resolution for a long time; dual-wavelength dual LD ​​can improve measurement resolution and anti-interference ability, but the discrete structure of the double tubes has the problem of difficulty in adjusting the irradiation at the same point

The injection current modulation of the semiconductor laser self-mixing interferometer is a typical method to improve the accuracy, but the current injection will also change the output light wavelength and introduce intensity noise; the external cavity length modulation is another improvement method, but it requires piezoelectric The ceramic driver drives the linear motion of the semiconductor laser, which not only increases the volume and cost of the instrument, but also has nonlinear problems such as hysteresis, which will cause inevitable measurement errors; It will not affect the laser system itself, has high measurement accuracy and wide range, and is very meaningful in industrial applications, but it needs to add an expensive electro-optic modulator, which is not cost-effective, and has high requirements for the polarization of the output laser.

Moreover, the measurement resolution of the above-mentioned methods of improving accuracy is single and non-adjustable, which cannot meet the measurement needs of different working conditions in the manufacturing industry.

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