Planar light waveguide measuring method for micro-displacement

Abstract

A micro-displacement planar optical waveguide measurement method. The laser emitted by the laser is incident on the prism. When the coupling condition is satisfied, the light enters the metal film deposited on the prism, the air gap, and the metal film deposited on the optical glass. In the double-sided metal-clad waveguide, the reflected light is extremely sensitive to changes in the thickness of the air gap, that is, the thickness of the air waveguide layer. The light intensity reflected from the bottom of the prism changes with the distance between the optical glass sheet and the prism. Through Detect the change of reflected light intensity to measure the change of the position of the optical glass relative to the prism, so as to obtain the displacement of the object to be measured. Compared with the prior art, the invention can be widely used in the micro-displacement measurement of dams, buildings and earth's crust. The invention can realize high sensitivity and fast real-time measurement, and the measurement method is very simple.

Description

technical field [0001] The invention relates to a measurement method, in particular to a micro-displacement optical waveguide measurement method. It belongs to the technical field of precision measurement. Background technique [0002] Measuring micro-displacement has a wide range of applications in long-term monitoring of buildings and bridges and detection of earthquakes. The traditional method of micro-displacement measurement is laser interferometry. The principle of this method is: usually the laser interferometer has two arms, one is the reference arm and the other is the detection arm. When the laser beam enters the interferometer, the two laser beams interfere after passing through the reference arm and the detection arm, forming stable interference fringes. When a small displacement occurs in the outside world, the arm length of the detection arm will change, and at this time, the phase of the reflected laser light by the plane mirror on the end face of the detec...

AI Technical Summary

Problems solved by technology

But in general, the use of interferometric technology to measure micro-displacement has defects: (1) Usually two paths of light (one path of reference light and one path of detection light) are used. Since the two paths of light pass through different spatial regions, external disturbances ( Such as: air flow disturbance, ground vibration, etc.) will be coupled into the optical path, manifested as external disturbance of optical path difference, and finally reflected in the quality of the interference pattern and the movement of the fringes; (2) Micrometry by laser interferometry When shifting, the interference fringes and their movement are usually recorded by the CCD, according to the Rayleigh criterion: when two interference fringes are too close (less than the Rayleigh limit), they cannot be distinguished; (3) the fringes formed by laser interference The width and the size of each dot matrix unit on the CCD used to record the interference fringe have an impact on the interference fringe and its movement measurement