Fiber bragg grating sensing system based on narrow-band scanning light source and operation method

Abstract

The invention discloses a fiber bragg grating sensing system based on a narrow-band scanning light source and an operation method. In the system, one of narrow-band light wave laser beams which are outputted by a tunable laser and have periodical changeable wavelength is divided into N paths to be incident into N sensor channels; the FBGs (fiber bragg grating) with non-overlapping wavelength change range in each sensor channel are arranged from short wavelengths to long wavelengths, from near to far according to the characteristics; another path is entered to an etalon of a calibrating channel; reflected light of each sensor channel and transmission light of the etalon are accessed to FPGA (field programmable gate array) through photoelectric detectors and a signal processing circuit; the output end of FPGA is connected with an industrial personal computer; the control signal is accessed to the tunable laser. The operation method is as follows: the narrow-band laser scanned by the tunable laser periodically is accessed to each sensor channel, and reflected when the wavelength of the laser is identical to the characteristic length wave of certain FBG; another laser path is transmitted through the etalon; the two paths of laser are converted into electric signals to be accessed to the industrial personal computer, so as to obtain the FBG wavelength variation. The fiber bragg grating sensing system can continuously scan with real-time wavelength calibration precision up to 1 micro strain. The FPGA are parallel to collect and process the wavelength, so that the demodulation speed is high.

Description

technical field [0001] The invention relates to fiber grating sensing technology, in particular to a fiber grating sensing system and an operating method based on a narrow-band scanning light source. Background technique [0002] At present, most fiber grating sensing systems are composed of broadband light sources, optical beam splitters, fiber grating sensors, tunable filter devices, photodetectors and corresponding circuit systems. Under the influence of environmental strain or temperature change, the reflection wavelength of the fiber grating sensor changes. After passing through the tunable filter device, it is received by the photodetector and demodulated by the circuit system to obtain the current reflection wavelength. Compared with the initial wavelength, according to The change of the current reflection wavelength can obtain the strain or temperature change of the sensor location of the fiber Bragg grating. [0003] Since only a small part of the broadband light s...

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Problems solved by technology

[0003] Since only a small part of the broadband light source is used at each moment in the existing fiber grating sensing system, the utilization rate of the light source is low, and the signal-to-noise ratio of the sensing signal is poor.

And because the backend can only scan one channel each time it scans the frequency, it is difficult to realize the multiplexing of fiber grating sensors and real-time wavelength calibration, which directly affects the number of sensors that can be demodulated and the demodulation accuracy

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