Non-contact micro-vibration measuring system based on non-equilibrium Michelson fiber-optic interferometer

Abstract

The invention discloses a non-contact micro-vibration measuring system based on a non-equilibrium Michelson fiber-optic interferometer, which belongs to the technical field of fiber-optic sensing. The non-contact micro-vibration measuring system is characterized in that lights pass through a narrow-band light source, a coupler and the non-equilibrium Michelson fiber-optic interferometer in sequence, wherein one path of the lights irradiates to the surface of an object vertically by an optical-fiber self-focusing lens, then returns and is coupled into optical fiber; the other path of the lights is returned by a reflecting device at the tail end of the optical fiber of a reference arm; the two paths of lights pass through the coupler, a photoelectric coupler (PD) and a data processing module; simultaneously, the data processing module generates carriers waves to control a phase modulator on an interference arm; and finally, a result is obtained by a phase demodulation technology of a phase generation carrier (PGC) based on calculation of arc tangent (ARCTAN). The non-contact micro-vibration measuring system has the beneficial effects that due to the adoption of the combination of the Michelson fiber-optic interferometer and the phase generation carriers based on calculation of the arc tangent, the flexibility is high, the response is good, no influence by factors of light intensity and visibility drifting is caused, and the online measurement on non-contact micro-vibration can be realized.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and relates to a non-contact micro-vibration measurement system based on an unbalanced Michelson optical fiber interferometer. Background technique [0002] The early measurement system using the Michelson interferometric principle was in the form of a lens, but it was gradually replaced by a fiber optic Michelson interferometer because of its large size and inconvenient operation. The interferometric sensor has high sensitivity and precision, and the demodulation accuracy of the interferometric signal directly affects the detection accuracy of the interferometric sensor. The existing demodulation scheme uses the interference fringe counting method to calculate the change of the interference phase, and then restores the vibration signal according to the phase change and the change of the optical path of the measuring arm. This method is greatly affected by light intensity, requires...

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Problems solved by technology

This method is greatly affected by light intensity, requires high contrast between the two beams of light, and cannot accurately measure signals and vibration directions with phase changes greater than π amplitude, which limits the measurement application range of fiber optic Michelson interferometers

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