Micro-rotation-angle measuring method and system based on laser double-feedback self-mixing interference

Abstract

The invention discloses a micro-rotation-angle measuring method based on laser double-feedback self-mixing interference, and the method comprises the steps: collecting a double-feedback self-mixing interference signal through a signal processing module on the basis of double-feedback self-mixing interference, converting the double-feedback self-mixing interference signal into a voltage signal, calculating the amplitude of the double-feedback interference signal through computer software, and enabling the amplitude to serve as reference signal power (p1); the signal processing module collects a double-feedback self-mixing interference signal generated due to the change of the rotation angle of the rotation angle object and converts the double-feedback self-mixing interference signal into a voltage signal, and the amplitude of the double-feedback self-mixing interference signal at the moment is calculated to serve as measured signal power (p2); and finally, according to the relational expression that the power (p2) of the measured signal is influenced by the micro-rotation angle amount, the micro-rotation angle amount is reversely calculated, the angle measurement range is larger and can be about-0.7 rad to + 0.7 rad, high-precision micro-rotation angle measurement is achieved in a large range, and the requirement for nanoscale rotation angle measurement is met.

Description

technical field [0001] The invention relates to optical applications, in particular to a method and system for measuring the rotation angle of an object by using laser self-mixing interference effect. Background technique [0002] The self-mixing interference (Self-mixing Interference, SMI) effect means that the light wave emitted from the laser is reflected back to the laser cavity by an external object, and interferes with the light wave in the laser cavity. Since the feedback light reflected back to the laser cavity carries the information of the external object when it is reflected by the external object, and then interferes with the light in the cavity, it will modulate the output characteristics of the laser, so that the measurement of the physical quantity of the target object can be realized. [0003] The traditional self-mixing interference system has only one optical channel, which has the advantages of compact structure, simple structure, and strong anti-interfere...

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Problems solved by technology

[0004] When the laser beam is incident on a rotating object, if the laser beam deviates from the rotation center of the measured object, the angle change of the measured object will lead to the change of the optical path of the feedback light, and the phenomenon of laser self-mixing interference will appear, see Chinese patent document CN1963384A , a micro-angle measurement method and device based on laser self-mixing interference. The angle measurement method is based on single-light feedback self-mixing interference technology, and the measurement accuracy is high. However, when the angle of the measured object changes greatly, the feedback light cannot return to the laser. Self-mixing interference is formed in the cavity, so the measurable angle range of this method is very small, only -0.0007rad to +0.0007rad, this measurement accuracy is far from meeting the high-precision measurement requirements

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