Laser phase grating interference displacement sensor

Abstract

A laser phase grating interference displacement sensor includes a semiconductor laser, a parallel spring, a transmission grating, a ±1-level plane mirror, a beam splitting prism, an interference light plane mirror, a beam expander lens, a photoelectric receiver and a signal processing circuit. The laser and the transmission grating are respectively fixed on the front and rear brackets of the parallel springs; the connecting rod is connected to the lower end of the rear bracket of the parallel springs, and is connected to the measuring rod through the touch ball. The measuring rod is installed on the bearing, and the probe is fixed on the measuring rod. The other end: the light beam emitted by the laser passes through the transmission grating, the plane mirror, and the beam splitter in turn to generate interference fringes. After the interference fringes are expanded by the lens, they are received by the photoelectric receiver, and the optical signal is converted into an electrical signal, and then sent to the signal processing circuit. output after processing. The invention has the characteristics of large measuring range, high measuring precision, simple structure and low cost. The sensor can be used to measure the surface profile and surface roughness of workpieces, with a measurement range of 0-3mm and a resolution of 6nm.

Description

technical field [0001] The invention belongs to displacement sensor technology, in particular to a laser phase grating interference displacement sensor. Background technique [0002] With the rapid development of surface profile measurement technology, in order to meet the increasing requirements of surface profile measurement, the problem of developing a displacement sensor with large range, high precision and low cost has become very important. Surface profile measurement generally uses inductive displacement sensors, which have the problems of small measurement range, high cost and low precision. At present, there are mainly two kinds of large-range contour measurement displacement sensors: one is the contour measurement displacement sensor using the principle of laser interference ([1] Xiao Hong, Wang Xuanxuan, Xie Tiebang. Rolling bearing surface contour measuring instrument. Bearing, 6, 2004, p.30~33), compared with grating interferometry, the accuracy of laser interf...

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Problems solved by technology

The second is to use cylindrical grating interference profile measurement displacement sensor ([2] Jiang Xiangqian, Li Zhu, Xie Tiebang. Theoretical research on the measurement of surface morphology by holographic grating interferometry. Journal of Huazhong University of Science and Technology, 22(2), 1994, p.60~ 64), the sensor uses a cylindrical grating, which is difficult to process and difficult to install and position

However, the cylindrical grating processing must strictly ensure the curvature radius and surface quality of the cylindrical surface, which makes the sensor cost high

In addition, the cylindrical grating profile measurement displacement sensor is difficult to install, has high requirements for bearings, and a slight deviation in installation and manufacturing will prevent the grating from interfering, and the photocell cannot receive effective signals, resulting in measurement failure.

And the linear difference of its measurement, the measurement range and measurement accuracy are far from the theoretical analysis value, the actual measurement range is 1mm, and the measurement accuracy is 10nm

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