Phase demodulation device and demodulation method capable of suppressing light-intensity fluctuation noise

Abstract

The invention discloses a phase demodulation device and demodulation method capable of suppressing light-intensity fluctuation noise. The phase demodulation device comprises a fiber interferometer and a digital demodulation device. According to the device and method, an improvement is carried out on a conventional phase generation carrier algorithm; multiplying operation is carried out on a fundamental frequency component and a frequency doubling component of a tested phase, and meanwhile, multiplying operation is carried out on the differential value of the fundamental frequency component and the differential value of the frequency doubling component; then, division operation is carried out on the two products above to remove noise caused by light-intensity fluctuation; and the tested phase is calculated through an integration method. Meanwhile, a noise reduction demodulation algorithm is integrated in FPGA and DSP large-scale high-speed signal processors; and according to the characteristics of high parallel processing capability of an FPGA and excellent floating-point calculation performance of a DSP, differential and corresponding phase calculation are partially realized in the two processors respectively, thereby ensuring real-time performance. The phase demodulation device and method suppress the light-intensity fluctuation noise effectively, improve long-term stability and can be widely applied to the fields of high-precision fiber measurement and fiber sensing and the like.

Description

technical field [0001] The invention belongs to the field of optical (fiber) interferometer measurement, in particular to a phase demodulation device and demodulation method for suppressing light intensity fluctuation noise. Background technique [0002] Fiber optic interferometric sensors have the highest sensitivity and dynamic range among all fiber optic sensor types. The basic principle is to use the phase change in the interferometer to measure other physical quantities such as temperature, stress, displacement, acceleration, etc. The Phase Generation Carrier (PGC) algorithm proposed by the U.S. Naval Laboratory in 1982 is one of the most classic algorithms in the phase demodulation of interferometric fiber optic sensors. The PGC algorithm can be directly realized by modulating the light source, which ensures that the sensor has a compact structure and a small size. features. [0003] The traditional PGC demodulation algorithm process is to perform operations such as m...

AI Technical Summary

Problems solved by technology

However, this method needs to add an additional 3×2 coupler on the optical path, and at the same time additionally collect 2 reference signals, and the demodulation device must also complete the calculation of these 2 reference signals, that is, the hardware overhead will increase by 3 more than double

Another institution that has done in-depth research on hydrophones is the National University of Defense Technology. Dr. Liang Xun discussed in depth in his dissertation the amount of noise that will be introduced by the fluctuation of the light intensity B value and the modulation depth C in the PGC demodulation algorithm. He proposed In the hydrophone array, the method of using multi-channel signal correlation to suppress the noise value, the same, will undoubtedly bring greater hardware overhead

The above two methods use the spatial correlation of the demodulation optical path and the time correlation of the demodulation signal to suppress noise. The advantage is that it can remove the common mode noise caused by the light source in each path. The disadvantage is that an additional reference optical path and Demodulation hardware corresponding to the reference optical path

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