A multi-channel low-coherence interferometric demodulation method capable of matching any channel of the sensor

Abstract

The invention discloses a multi-channel low-coherence interference demodulation method capable of realizing arbitrary channel matching of a sensor. The multi-channel low-coherence interference demodulation method comprises the steps of: step 1, calculating a low-precision envelope peak value position Kp by adopting Fourier transform method, calculating a low-precision absolute phase estimated value phi<est>, restoring an absolute phase phi of low-coherence interference fringes according to a fringe order n of relative phase restoration interference fringes, and calculating a true envelope peakvalue position Kd of the low-coherence interference fringes; step 2, selecting an arbitrary sensing channel as a calibration channel, acquiring a true envelope peak value position array correspondingto a scanning pressure array in the channel, and establishing a corresponding relationship between an F-P sensor low-coherence interference fringe envelope peak value position and external pressure;step 3, calculating a scanning optical path difference OPD generated by a polarization low-coherence interference demodulator and an envelope peak value position compensation amount delta K among different sensing channels; step 4, and calculating a compensated envelope peak value position Kr, and demodulating to obtain a measured pressure value of the corresponding sensor channel by utilizing a corresponding relationship between the envelope peak value position Kr and the external pressure. The multi-channel low-coherence interference demodulation method realizes multi-channel applicable demodulation of the F-P sensor.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a low-coherence interference demodulation method suitable for multi-channel application of Fabry-Perot (F-P) sensors. Background technique [0002] Low-coherence interferometry is an important measurement method in the field of optical interference, and is widely used in the fields of three-dimensional shape detection, optical coherence tomography, and optical fiber sensing, such as pressure, temperature, and refractive index measurements. [0003] The combination of low-coherence interferometry and multi-channel multiplexing sensing applications has the advantages of simultaneous measurement of multiple points, high sensing accuracy, and low cost of sensor expansion. At present, wavelength division multiplexing and time division multiplexing are relatively common. Among them, the wavelength division multiplexing method uses light sources with different spectral cen...

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Problems solved by technology

However, affected by factors such as non-vertical incidence of the wedge beam, different positions of the sensing channels, non-ideal crystal processing, and inconsistent cavity lengths of mass-produced F-P sensors, in order to ensure the accuracy of Fabry-Perot (F-P) sensor demodulation Accuracy and reliability usually require calibration of F-P sensors with a specific sensing channel

The calibration operation makes the F-P sensor demodulate only on the corresponding calibration channel, but cannot be applied to other demodulation channels, which severely limits the application of the F-P sensor in multi-channel multiplexing sensing

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