Laser vibration displacement sensor and measuring method thereof

Abstract

The invention provides a laser vibration displacement sensor and a measuring method of the laser vibration displacement sensor. A laser device emits laser, the laser is projected to a vibration object through a collimation system, perpendicularly scattered light returns to the laser device through the collimation system, and then a self-mixing interference system is formed. A detector measures the output power of the laser device and enables high-frequency vibration measurement of the vibration object to be achieved through signal modulation. The light enters a focusing system through diagonal scattering of the vibration object, positions of focusing light spots are obtained on the scattering detector in order to form a laser triangulation structure, the absolute distance of the object can be obtained in an inversion mode through the positions of the light spots on the scattering detector, and low-frequency displacement change of the vibration object can be measured. According to the laser vibration displacement sensor and the measuring method of the laser vibration displacement sensor, organic combination of the laser triangulation and the laser self-mixing technology is achieved under the situation that systematic complexity is not increased, and the functions of measuring high-frequency vibration and low-frequency displacement change are achieved.

Description

technical field [0001] The invention belongs to the field of precision measurement and relates to a vibration and displacement sensor, in particular to a vibration and displacement sensor combined with laser self-mixing technology and laser triangulation and a measuring method thereof. Background technique [0002] Laser triangulation is widely used in the field of measurement, mainly for distance, displacement and other measurements; but for vibration changes with high frequency, the detector CCD / CMOS is required to work at a high frame rate, which will inevitably reduce exposure time and affect Image Resolution. In addition, the detector CCD / CMOS works at a driving frequency of 10MHz. If the pixel points are 2K, the frame rate of the detector is 5KHz. For vibration, if ten points are measured in one cycle, the maximum vibration frequency is 500Hz; thus Laser triangulation is difficult for vibrations with frequencies above 500 Hz. [0003] The laser self-mixing technology...

AI Technical Summary

Problems solved by technology

[0002] Laser triangulation is widely used in the field of measurement, mainly for distance, displacement and other measurements; but for vibration changes with high frequency, the detector CCD / CMOS is required to work at a high frame rate, which will inevitably reduce exposure time and affect Image Resolution

In addition, the detector CCD / CMOS works at a driving frequency of 10MHz. If the pixel points are 2K, the frame rate of the detector is 5KHz. For vibration, if ten points are measured in one cycle, the maximum vibration frequency is 500Hz; thus Laser triangulation is difficult for vibrations with frequencies above 500 Hz

[0003] The laser self-mixing technology has a simple structure, and only needs lasers and detectors to form a vibration detection system. However, according to the conclusion of Chapter 5 of Dr. For low speed (less than 70mm / s) measurement accuracy is not high

For low-frequency vibration, the corresponding speed is generally not high, so the laser self-mixing technology needs to be improved for low-frequency vibration measurement

[0004] In addition, the requirements of the laser used in the laser self-mixing technology generally use a single longitudinal film to operate, the line width is required to be less than 1GHz, and the output power is several mW semiconductor lasers, but there are few visible light lasers that meet these conditions, and the mass production is cheap. Semiconductor lasers for communication are commonly used in the infrared band

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