CN110082068A - A kind of optic fiber grating wavelength demodulating system and method with wavelength debugging functions - Google Patents
A kind of optic fiber grating wavelength demodulating system and method with wavelength debugging functions Download PDFInfo
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- CN110082068A CN110082068A CN201910227186.7A CN201910227186A CN110082068A CN 110082068 A CN110082068 A CN 110082068A CN 201910227186 A CN201910227186 A CN 201910227186A CN 110082068 A CN110082068 A CN 110082068A
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
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Abstract
The present invention relates to a kind of optic fiber grating wavelength demodulating system and method with wavelength debugging functions, this method is directed to length scanning formula optic fiber grating wavelength demodulating system, and the optical signal by reflecting fiber-optic grating sensor tail end and reference path intensity of light source signal time difference realize unknown fiber linear measure longimetry.Wavelength amendment demodulation method of the invention includes wideband light source, tunable filter, etalon, beam splitter, photodetector and the modules such as control and signal processing circuit, pass through the data decimation to reference path optical signal and sensing optical signal, using the methods of cross correlation algorithm, minimum mean square self-adaption filter method, realize with reference to the calculating with sense light signal time delay.Cause to demodulate wavelength value offset problem to solve the existing connection sensor fiber length of length scanning formula optic fiber grating wavelength demodulating system, guarantees that Wavelength demodulation system demodulates accuracy, improve sensor accuracy class, there is very strong engineering practical value.
Description
Technical field
The invention belongs to fiber optic sensor technology field, mainly a kind of optic fiber grating wavelength with wavelength debugging functions
Demodulating system and method.
Background technique
Fiber-optic grating sensor due to its small in size, light-weight, corrosion-resistant, high sensitivity, not by electromagnetic interference, cost
Low, the advantages that being easily integrated, it is applied to optical fiber temperature-depth chain, optical fiber temperature deep profile instrument, fibre optic hydrophone etc., in marine hydrology
The military, civilian fields such as monitoring, underwater sound monitoring and non-sound antisubmarine detection have broad application prospects.
Fiber-optic grating sensor is to realize physics using the characteristic of fiber grating reflected light wavelength with temperature, stress variation
The measurement of amount, therefore the measurement precision of fiber grating reflected light wavelength determines the performance of sensor, optic fiber grating wavelength solution
Tune method mainly has spectrophotometric spectra detection method, Wavelength Scanning Method, interferometry etc., and wherein Wavelength Scanning Method is due to system
Simply, the advantages that measurement accuracy is high, multiplexing capacity is strong, price is low, stability is high has become the preferred manner of industrial application.
However, the fiber lengths that length scanning formula optic fiber grating wavelength demodulation method has connection sensor can cause wavelength
The problem of demodulation value deviates, i.e., same fiber-optic grating sensor, the fiber lengths of connection are longer, and Wavelength demodulation value is bigger.By passing
Deviation between Wavelength demodulation value and actual value caused by sensor fiber lengths will lead to the drop of fiber-optic grating sensor measurement accuracy
It is low.For this problem, currently used main method is the fiber lengths of the sensor of measurement connection in advance, further according to wavelength solution
The relationship of wavelength shift caused by the sensor fiber length of adjusting system and corresponding factor, to the optic fiber grating wavelength value of demodulation into
Row amendment.This method operating process is cumbersome, inconvenient to engineer application bring.Therefore studying one kind has automatic amendment by optical fiber
The length scanning formula optic fiber grating wavelength demodulation method that length causes Wavelength demodulation value to deviate has significant application value.
Summary of the invention
It will cause wavelength for connection sensor fiber length existing for length scanning formula optic fiber grating wavelength demodulation method
The problem of demodulation value deviates, the present invention provides a kind of optic fiber grating wavelength demodulating system and method with wavelength debugging functions,
By resolving the length of unknown fiber coil in incoming fiber optic grating wavelength demodulating system, so that it is inclined to calculate the wavelength being not introduced into
Difference is simultaneously finally removing some effects, final to realize wavelength debugging functions, efficiently solves fiber lengths and causes to demodulate wavelength
The offset problem of value ensure that the demodulation accuracy of Wavelength demodulation system, improve the measurement accuracy of sensor.
The object of the present invention is achieved by the following technical solutions.A kind of fiber grating with wavelength debugging functions
Wavelength demodulation system, including wideband light source, tunable optic filter, beam splitter A, etalon, beam splitter B, beam splitter C, circulator,
Fiber optic coils (testing fibers of unknown lengths), fiber-optic grating sensor, detector A, detector B, detector C, detector D,
Control and signal processing circuit；The wideband light source output demodulation spectrum, into tunable optic filter, at control and signal
Circuit output triangular wave driving signal is managed into tunable optic filter, tunable optic filter is under the driving of driving signal, to defeated
Optical signal is scanned and exports, and the optical signal of output enters beam splitter A described in beam splitter A3 and input light is divided into two-way,
It is input to beam splitter B all the way as reference signal, the another way of Wavelength demodulation and is input to circulator as sensing optical signal；It is described
Beam splitter B input optical signal is divided into two-way, all the way enter etalon input signal is handled, generate comb δ function formula it is strong
Signal enters detector A0 to degree, another way is directly inputted to detector B as intensity of light source signal；Enter the light letter of circulator
Number by being input in fiber-optic grating sensor after fiber optic coils, it is defeated that the optical signal of fiber-optic grating sensor reflection passes through former road again
Enter beam splitter C out；Sensing optical signal is divided into two-way and respectively enters detector C and detector D by the beam splitter C.
The wavelength scanning range of the tunable optic filter is greater than the spectral region of wideband light source.
A kind of optic fiber grating wavelength demodulation method with wavelength debugging functions, steps are as follows: the control and signal
The signal that four tunnel photoelectric conversion of processing circuit synchronous acquisition is completed, wherein the first via and third road are for normally demodulating sensor
Wavelength data value, the second road and the 4th tunnel are used to resolve the length of fiber optic coils, realize sweeping for wavelength using tunable optic filter
It retouches, when the optical wavelength of length scanning optical signal is identical as sensing grating wavelength, the light of the wavelength will reflect, the light of commplementary wave length
Will transmission, the optical signal reflected by wavelength correction algorithm to fiber-optic grating sensor tail end and the light source that reference path detects are strong
The time difference for spending signal realizes the measurement of fiber lengths.
The wavelength correction algorithm is with the light intensity signal of detector B acquisition for reference, whether there is or not fiber optic coils to access
Two kinds in the case of, the reflected signal of fiber-optic grating sensor has the offset of position relative to light intensity signal, and the offset is then
It is that fiber optic coils introduce, data processing operation is carried out to above-mentioned signal, calculates reference and sense light signal time delay, further according to
Length scanning finally calculates wavelength shift, to realize debugging functions.
The invention has the benefit that the wavelength of the invention patent review one's lessons by oneself orthofunction easily and effectively solve length scanning
The fiber lengths of the existing connection fiber-optic grating sensor of formula optic fiber grating wavelength demodulating system cause the offset for demodulating wavelength value
Problem ensure that the demodulation accuracy of Wavelength demodulation system, improve the measurement accuracy of sensor.
Detailed description of the invention
Fig. 1 is system global structure block diagram of the invention.
Fig. 2 show light intensity signal and sensor signal relative position comparison diagram.
Description of symbols: wideband light source 1, tunable optic filter 2, beam splitter A3, etalon 4, beam splitter B5, beam splitter
C6, circulator 7, fiber optic coils 8, fiber-optic grating sensor 9, detector A10, detector B11, detector C 12, detector D13,
Control and signal processing circuit 14.
Specific embodiment
Below in conjunction with attached drawing, the present invention will be described in detail:
As shown in Figure 1, a kind of optic fiber grating wavelength demodulating system with wavelength debugging functions, including wideband light source 1, can
Tuned filter 2 (Tunable Fabry-Perot Filter), beam splitter A3, etalon 4 (F-P etalon), beam splitter B5, beam splitter C6, annular
Device 7, fiber optic coils 8, fiber-optic grating sensor 9, detector A10, detector B11, detector C 12, detector D13, control with
Signal processing circuit 14；Wherein, the wavelength scanning range of the tunable optic filter 2 is greater than the spectral region of wideband light source 1.
◆ wideband light source issues broad band wavelength optical signal；
◆ Tunable Fabry-Perot Filter sweeps the optical wavelength of light source output under the driving of ladder-like triangle wave voltage signal
It retouches；
◆ beam splitter repeatedly splits optical signal, for reaching different functions；
◆ F-P etalon, the reference signal for generating the comb δ function formula of standard, as Wavelength demodulation；
◆ photodetector is used for photoelectric converting function, and optical signal is converted into electric signal for subsequent processing；
Control realizes optical path driving with signal processing circuit and control, data acquisition, wavelength correction algorithm is realized and wavelength
The functions such as demodulating algorithm realization.
The output demodulation spectrum of wideband light source 1, into tunable optic filter 2, control and signal processing circuit 14
Triangular wave driving signal is exported into tunable optic filter 2, tunable optic filter 2 is under the driving of driving signal, to input light
Signal is scanned and exports, and the optical signal of output enters beam splitter A3；Input light is divided into two-way by the beam splitter A3, and one
Road is input to beam splitter B5 as reference signal, the another way of Wavelength demodulation and is input to circulator 7 as sensing optical signal；It is described
Beam splitter B5 input optical signal is divided into two-way, all the way enter etalon 4 input signal is handled, generate comb δ function formula
Strength signal enters detector A10, another way is directly inputted to detector B11 as intensity of light source signal；Enter circulator 7
Optical signal by being input in fiber-optic grating sensor 9 after fiber optic coils 8, the optical signal that fiber-optic grating sensor 9 reflects is again
Enter beam splitter C6 by the output of former road；Sensing optical signal is divided into two-way and respectively enters detector C 12 by the beam splitter C6
With detector D13, wherein detector D13 has high-gain, for the weak feature of optical fiber tail-end reflection signal, transducing signal
Light intensity background amplitude embodies, and corrects convenient for subsequent wavelength.
The present invention discloses a kind of optic fiber grating wavelength demodulation method with wavelength debugging functions, reference path light
The data decimation (the spectrum edge of wideband light source) of signal and sensing optical signal, using cross correlation algorithm, minimum mean square self-adaption
The methods of filter method is realized with reference to the calculating with sense light signal time delay, further according to length scanning velocity interpolation wavelength shift
Calculating.Specific step is as follows: the signal that the control and 14 synchronous acquisition of signal processing circuit, four tunnel photoelectric conversion is completed,
Wherein the first via and third road are for normally demodulating wavelength data value, the second road and the 4th tunnel of sensor for resolving optical fiber cable
The length of circle 8 realizes the scanning of wavelength using tunable optic filter, when the optical wavelength and sense light lattice wave of length scanning optical signal
The light of appearance while the wavelength will reflect, and the light of commplementary wave length will transmit, by wavelength correction algorithm to fiber-optic grating sensor
The time difference of the intensity of light source signal of the optical signal and reference path detection of tail end reflection realizes the measurement of fiber lengths.It is described
Wavelength correction algorithm be with the light intensity signal of detector B11 acquisition for reference, whether there is or not two kinds of situations that fiber optic coils 8 access
Under, the reflected signal of fiber-optic grating sensor 9 has the offset of position relative to light intensity signal, which is then fiber optic coils
8 introducings, the data processing operations such as cross correlation algorithm, minimum mean square self-adaption filter are carried out to above-mentioned signal, calculate ginseng
Examine with sense light signal time delay, wavelength shift is finally calculated further according to length scanning, to realize debugging functions.
System specific workflow is as follows:
1) wideband light source output demodulation spectrum, into tunable optic filter；
2) control exports triangular wave driving signal to tunable optic filter with signal processing circuit；
3) tunable optic filter is scanned input optical signal and exports under the driving of driving signal, the light of output
Signal enters beam splitter A, and the wavelength scanning range of tunable optic filter is greater than the spectral region of wide spectrum light source；
4) input light is divided into two-way by beam splitter A, is input to reference signal, another of the beam splitter B as Wavelength demodulation all the way
It is input to circulator all the way as sensing optical signal；
5) input optical signal is divided into two-way by beam splitter B, enters etalon all the way and input signal is handled, generate comb
Shape spectral intensity signal enters detector A, another way is directly inputted to detector B as intensity of light source signal；
6) optical signal of circulator is entered by being input to FBG sensing after fiber optic coils (testing fibers of unknown lengths)
In device, the optical signal of FBG sensor reflection passes through former road output again and enters beam splitter C；
7) sensing optical signal is divided into two-way and respectively enters detector C and D by beam splitter C, and wherein detector D has high increase
Benefit embodies the light intensity background amplitude of transducing signal, is convenient for subsequent wavelength for the weak feature of optical fiber tail-end reflection signal
Amendment；
8) signal completed with four tunnel photoelectric conversion of signal processing circuit synchronous acquisition is controlled；The wherein first via and third road
Wavelength data value, the second road and the 4th tunnel for normally demodulating sensor are used to resolve the length of fiber optic coils；
Fig. 2 show light intensity signal and sensor signal relative position comparison diagram, compares the figure and introduces fiber optic coils length
Computation is as follows:
1) right figure is enlarged drawing of the left figure in algorithm realization position in figure；
2) blue line is the intensity of light source signal of detector B acquisition in figure, red line is detector D acquisition without optical fiber
The signal of fiber-optic grating sensor, fiber grating when having fiber optic coils access that green line is detector D acquisition when coil accesses
The signal of sensor；
3) influence of the light intensity signal due to not will receive fiber optic coils, so relative position will not change, with the letter
Number as reference, it can be seen that have sensor signal ratio when fiber optic coils access do not have coil access phase contraposition postpone shifting,
The position moved back is then the offset that fiber optic coils introduce；
The data processing operations such as cross correlation algorithm, minimum mean square self-adaption filter are carried out to the signal in figure, are calculated
With reference to sense light signal time delay, wavelength shift is finally calculated further according to length scanning, to realize debugging functions.
It is understood that it will be understood by those skilled in the art that being subject to technical solution of the present invention and inventive concept
It all should fall within the scope of protection of the appended claims of the present invention with replacement or change.
Claims (4)
1. a kind of optic fiber grating wavelength demodulating system with wavelength debugging functions, it is characterized in that: include wideband light source (1), can
Tuned filter (2), beam splitter A (3), etalon (4), beam splitter B (5), beam splitter C (6), circulator (7), fiber optic coils
(8), fiber-optic grating sensor (9), detector A (10), detector B (11), detector C (12), detector D (13), control with
Signal processing circuit (14)；Wideband light source (1) the output demodulation spectrum, into tunable optic filter (2), control and letter
Number processing circuit (14) output triangular wave driving signal is in tunable optic filter (2), and tunable optic filter (2) is in driving signal
Driving under, input optical signal is scanned and is exported, the optical signal of output enters beam splitter A (3)；The beam splitter A
(3) input light is divided into two-way, reference signal, the another way for being input to beam splitter B (5) all the way as Wavelength demodulation are input to ring
Row device (7) is as sensing optical signal；Input optical signal is divided into two-way by the beam splitter B (5), enters etalon (4) all the way
Input signal is handled, comb δ function formula strength signal enters detector A (10), another way is directly inputted to detector for generation
B (11) is used as intensity of light source signal；The optical signal of circulator (7) is entered by being input to fiber grating after fiber optic coils (8)
In sensor (9), the optical signal of fiber-optic grating sensor (9) reflection passes through former road output again and enters beam splitter C (6)；Described
Sensing optical signal is divided into two-way and respectively enters detector C (12) and detector D (13) by beam splitter C (6).
2. the optic fiber grating wavelength demodulating system according to claim 1 with wavelength debugging functions, it is characterised in that: institute
The wavelength scanning range for the tunable optic filter (2) stated is greater than the spectral region of wideband light source (1).
3. a kind of method using the optic fiber grating wavelength demodulating system as described in claim 1 with wavelength debugging functions,
It is characterized by: the signal that the control and four tunnel photoelectric conversion of signal processing circuit (14) synchronous acquisition are completed, wherein the
All the way with third road for normally demodulating wavelength data value, the second road and the 4th tunnel of sensor for resolving fiber optic coils (8)
Length, using tunable optic filter realize wavelength scanning, when length scanning optical signal optical wavelength and sensing grating wavelength
The light of the wavelength will reflect when identical, and the light of commplementary wave length will transmit, by wavelength correction algorithm to fiber-optic grating sensor tail
The time difference of the optical signal of reflection and the intensity of light source signal of reference path detection is held to realize the measurement of fiber lengths.
4. the method for the optic fiber grating wavelength demodulation according to claim 3 with wavelength debugging functions, it is characterised in that:
The wavelength correction algorithm is with the light intensity signal of detector B (11) acquisition for reference, what is accessed whether there is or not fiber optic coils (8)
In the case of two kinds, fiber-optic grating sensor (9) reflected signal has the offset of position relative to light intensity signal, and the offset is then
It is that fiber optic coils (8) introduce, data processing operation is carried out to above-mentioned signal, calculates reference and sense light signal time delay, then
Wavelength shift is finally calculated according to length scanning, to realize debugging functions.
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| CN111830567A (en) * | 2020-06-29 | 2020-10-27 | 西北大学 | Time delay deviation correction system and correction method for geophone array signal |
| CN113252088A (en) * | 2021-05-18 | 2021-08-13 | 电子科技大学 | Multi-wavelength distributed optical fiber sensing system and method |
| CN113551701A (en) * | 2021-06-19 | 2021-10-26 | 湖北经济学院 | Bus type fiber grating demodulation system |
| CN119575131A (en) * | 2024-11-28 | 2025-03-07 | 江苏晋成半导体有限公司 | Optical chip testing system based on FPGA |
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