Phase-shifting high-speed low coherence interference demodulating device and method thereof

Abstract

The invention discloses a phase-shifting high-speed low coherence interference demodulating device and a method thereof. The device comprises a broadband light source, a coupler, a collimating lens and a demodulating light path, wherein light emitted from the broadband light source passes the collimating lens and enters an optical fiber fabry-perot sensor. Light signals demodulated by the optical fiber fabry-perot sensor then pass the coupler and enter the demodulating light path through the collimating lens. The light signals sequentially pass through a polarizer, a four-step birefringence phase shifter, an analyzer and detectors in the demodulating light path, wherein the four-step birefringence phase shifter and four corresponding detectors conduct uniformly-spaced four-point sampling towards interference signals using one quarter wavelength as a step-length, conducting range expansion, and realizing demodulation by using expanded relative phases. Compared with the prior art, the phase-shifting high-speed low coherence interference demodulating device and the method thereof have good stability and reliability, and can achieve low coherence interference demodulation at high speed.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to a phase-shift high-speed low-coherence interference demodulation device and method based on low-coherence technology and phase-shift technology. Background technique [0002] The low-coherence interference demodulation device is generally composed of two interferometers connected in series. Among them, the sensor interferometer can sense the change of the measured physical quantity in the outside world, and the scanning interferometer can scan and demodulate the optical path difference introduced by the sensor. or demodulation interferometer. According to the optical path difference scanning method, the interferometer can be divided into two types: the Michelson interferometer based on the interference arm scanning method (also known as the time scanning type) and the Fizeau interferometer based on the correlation method (also known as the space scanning type). Compared with...

AI Technical Summary

Problems solved by technology

Among them, the centroid or contrast method is relatively simple, but it is difficult to achieve high-precision demodulation, and the envelope method will introduce a large amount of calculation because it involves digital transformation techniques such as Fourier, Hilbert or Wavelet to extract the interference envelope, which limits the Its demodulation speed; some people also use the phase of the frequency domain to achieve demodulation, such as the spatial frequency domain algorithm (SFDA), the enhanced phase demodulation algorithm, etc. are all demodulation algorithms based on the frequency domain, similar to the envelope method, this Such methods also require Fourier changes to obtain phase information in the frequency domain, and are also not suitable for high-speed demodulation occasions.

Images