Multiscale quasi-distributed white light interferometric strain measurement device adopting common path compensation and method thereof

Abstract

The invention provides a multiscale quasi-distributed white light interferometric strain measurement device adopting common path compensation and a method thereof. The measurement device comprises a wide band light source, an optical fiber circulator, an adjustable Fizeau interferometer, a lead-in / lead-out optical fiber, an optical fiber sensor array, a photoelectric detector, a band-pass filter and a signal processing unit, wherein the adjustable Fizeau interferometer is composed of a gradient index lens and a movable scanning mirror, the distance between the two devices can be adjusted; the four ports of the optical fiber circulator are separately connected with the wide band light source, the adjustable Fizeau interferometer, the lead-in / lead-out optical fiber and the photoelectric detector closkwise; the other end of the lead-in / lead-out optical fiber is connected with the optical fiber sensor array; and the output end of the photoelectric detector is connected with the signal processing unit through the band-pass filter. By adopting the device and method of the invention, the multiscale quasi-distributed complete common-path optical path matching can be realized; the luminous power attenuation and loss can be reduced, the detectivity can be increased; and the optical structure of the optical system can be simplified, the cost can be reduced and the stability and reliability can be increased.

Description

technical field [0001] The invention relates to a multi-scale quasi-distributed white light interference strain measuring device. It can be used in the demodulation system of multiplexed fiber optic white light interference sensor array. The invention also relates to a multi-scale quasi-distributed white light interference strain measurement method. Background technique [0002] An interferometer that uses broad-spectrum light as a light source and optical fiber as a transmission medium is called a white light fiber optic interferometer. A traditional fiber optic white light interferometer generally includes a sensing arm and an adjustable reference arm, and signals transmitted along the sensing arm and reference arm are detected by photodetectors. If the optical path difference between the sensing arm and the reference arm is less than the coherence length of the light source, the two signals interfere. The characteristic of white light interference fringes is that there...

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Problems solved by technology

[0006] However, in the above-mentioned interferometer structure based on space division multiplexing, there are two problems without exception: one is the large power attenuation of the light source, the low efficiency of the light source, and only a small part of the signal light generated by the light source reaches the sensor array , and is received by the detector to form an interference signal. According to the optical path structure disclosed by W.V.Sorin, only about 1 / 4 of the light source power participates in the optical autocorrelation process, and the rest is attenuated by the coupler; the second is due to the optical path topology The symmetric characteristics of the light source and the detector are reciprocal in the optical path topology. In theory, at least the same value of the optical signal received by the detector is fed back to the light source.

However, excessive signal power feedback, especially for light sources with large spontaneous emission gain such as SLD and ASE, the feedback light will cause the resonance of the light source

In light cases, the power of the optical signal generated by the light source will be reduced; in severe cases, during white light interference, large interference signal power fluctuations will reduce the measurement accuracy of the optical self-coherence peak; in extreme cases, it will damage the light source and cause damage to the light source. irreparable damage

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