Fiber Bragg grating sensing system with wavelength scaleplate calibration function

Abstract

The invention discloses a fiber Bragg grating sensing system with the wavelength scaleplate calibration function. The system is composed of a broadband light source of an ASE light source and an optical isolator, a tunable F-P filter, a coupler, a circulator, an FBG sensor array, an etalon, a first photoelectric detector, a second photoelectric detector, a data acquisition device, a computer, anda tunable power supply. PZT hysteresis and creep compensation are carried out by controlling the driving voltage of the F-P filter and thus the wavelength interval of the transmission spectrum peak value of the etalon linearly changes with time, so that the wavelength of the transmission spectrum peak value, as the scale line of the wavelength scaleplate, of the etalon is calibrated and a precisewavelength reference is provided for wavelength demodulation of the sensing grating. The wavelength of the sensing grating can be measured precisely and thus the physical quantities such as temperature and strain can be measured accurately based on the wavelength information of the sensing grating.

Description

technical field [0001] The present invention relates to the technical field of Fiber Bragg Grating (Fiber Bragg Grating, FBG) sensing, in particular to an optical fiber sensing system that utilizes the peak wavelength of the transmission spectrum of an etalon as a reference wavelength and combines the F-P filter demodulation method to demodulate the FBG wavelength ; Specifically, a fiber Bragg grating sensing system with a wavelength scale calibration function. Background technique [0002] Fiber Bragg grating sensor is also called FBG sensor, the English name of fiber Bragg grating is FiberBraggGrating, referred to as FBG. Due to its small size, high precision, fast response, corrosion resistance, electromagnetic insulation and other excellent characteristics, FBG sensors have developed vigorously in the field of temperature and strain sensing of various structures in the past few decades. The measurement of temperature and strain by FBG can be realized by detecting the ch...

AI Technical Summary

Problems solved by technology

However, in practical applications, because the PZT in the F-P filter has undesirable characteristics such as hysteresis and creep, the output wavelengths of the F-P filter corresponding to the same driving voltage at different times are different, and the demodulation error is large. Therefore, it is necessary to focus on the hysteresis and creep of the PZT creep compensation control

Prior Art 1[Liu Kun, Jing Wencai, Liu Tiegen, et al. Application of nonlinear correction of F-P tunable optical filter in dynamic strain sensing[J]. Journal of Sensing Technology, 2008,21(7):1264 -1268] The quadratic curve fitting method is used to correct the driving voltage of the F-P tunable optical filter nonlinearly, but the hysteresis and creep effects of the PZT in the F-P filter are not investigated in the prior art 1, if the driving voltage obtained by a single measurement There is a random error in the voltage and the corresponding F-P filter output wavelength, which will lead to insufficient voltage compensation for hysteresis and creep, resulting in wavelength calibration errors

In the F-P filter demodulation system using the peak wavelength of the transmission spectrum of the etalon as the reference wavelength, since the transmission wavelength of the etalon is the same as the wavelength of the tunable F-P filter, due to the hysteresis and creep of the PZT in the F-P filter, The situation that the peak wavelength interval of the transmission spectrum of the etalon is not linear with the change of time causes the peak wavelength interval of the transmission spectrum of the etalon as "the scale line on the wavelength scale" to not change linearly according to time, that is, the scale lines on the wavelength scale are not equally spaced, which will give Subsequent demodulation of the sensing grating wavelength brings errors

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