Dual-wavelength nonlinear displacement demodulation method and system of optical fiber Fabry-Perot displacement sensor

Abstract

The invention discloses a dual-wavelength nonlinear displacement demodulation method and system of optical fiber Fabry-Perot displacement sensor, belonging to the technical field of optical fiber sensing. The system comprises an optical fiber Fabry-Perot displacement sensor, two paths of wave length tunable lasers, two optical fiber couplers, an optical fiber circulator, a wavelength division multiplexer, two photoelectric detectors and a data collection card. The method comprises the following steps of: 1) acquiring two paths of reflectance spectrums; 2) setting working wavelengths of the twopaths of lasers, and respectively determining initial phases; 3) performing phase conversion of the reflection spectrums, curve fitting and solving of an inverse function; 4) calculating the change quantity of the optical phase, and determining the change quantity of the cavity length; 5) and demodulating the nonlinear displacement according to the model. The dual-wavelength nonlinear displacement demodulation method and system can improve the measuring range of the traditional optical fiber Fabry-Perot displacement sensor, are high in demodulation precision, can overcome the problem of fuzzyphase, are flexible in demodulation, and can give evaluation for the reliability of the demodulation result.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to the displacement demodulation technology of an optical fiber Fabry-Perot displacement sensor. Background technique [0002] With the development of science and technology, the monitoring and measurement of tiny vibrations in complex environments is becoming more and more important. However, the commonly used Doppler vibrometers, strain gauges, optical fiber displacement sensors and other instruments for measurement cannot adapt to the measurement methods. The measurement of complex environments or the inability to achieve high-precision micro-vibration measurement or the measurement of a large vibration range cannot be met. As a sound field calculation method, Rayleigh integration can calculate the sound pressure at any point in the field as long as the vibration velocity distribution on the surface of the transducer is measured. In the measurement envi...

AI Technical Summary

Problems solved by technology

When the optical fiber Fabry-Perot displacement sensor measures vibration displacement, it mainly faces three problems: 1) The measurement range is small, and it is easy to exceed the range for large displacement measurement

3) Perform nonlinear displacement demodulation by modifying the working wavelength of the laser. If the wavelength is set close to the trough of the reflection spectrum, the positive displacement can be demodulated well, but the demodulation error of the negative displacement is large; if the wavelength is set close to the peak of the reflection spectrum, the negative The displacement in the direction can be demodulated very well, but the demodulation error in the forward displacement is large

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