CN102818531B - Dynamic strain measurement instrument based on multiple overlapped gratings - Google Patents

Dynamic strain measurement instrument based on multiple overlapped gratings Download PDF

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CN102818531B
CN102818531B CN201210335869.2A CN201210335869A CN102818531B CN 102818531 B CN102818531 B CN 102818531B CN 201210335869 A CN201210335869 A CN 201210335869A CN 102818531 B CN102818531 B CN 102818531B
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gratings
dynamic strain
overlapping many
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CN102818531A (en
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杨远洪
马游春
杨明伟
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Beihang University
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Abstract

The invention provides a dynamic strain measurement instrument based on multiple overlapped gratings. The dynamic strain measurement instrument comprises the multiple overlapped gratings, a wideband light source, a tunable filter, a positioning coupler, an etalon, a photoelectric detector and a demodulation and control circuit. The multiple overlapped gratings are formed in a way that a plurality of sensing gratings with center wavelengths being distributed at equal intervals are inscribed in an overlapped manner in a same area on a sensing optical fiber by selecting different phase templates, wherein the center wavelengths of a fiber Bragg grating, which are inscribed in the overlapped together, are continuously distributed at equal intervals within a wavelength scanning range of the tunable filter, so that sensing information of the same physical quantity to be measured can be continuously obtained for a plurality of times within each wavelength scanning period, and a peak value position and wavelength variation of each sensing grating in the multiple overlapped gratings, namely reconfigurable original dynamic strain signals, can be recorded. Therefore, the purpose of improving a measurement bandwidth of the dynamic strain signals based on a grating demodulation system of the tunable filter can be realized. According to the dynamic strain measurement instrument provided by the invention, the sensed measurement bandwidth of the fiber Bragg grating based on the tunable filter can be effectively improved, so that the high-speed and high-precision simultaneous measurement requirement of the dynamic strain signals can be met.

Description

A kind of dynamic strain measurement instrument based on overlapping many gratings
Technical field
The present invention relates to a kind of dynamic strain measurement instrument based on overlapping many gratings, be mainly used in sensing and the measurement of dynamic strain signal, belong to field of sensing technologies.
Background technology
Fiber grating can convert the variation of external environment (as stress, strain, vibration, temperature variation etc.) to the variation of self reflectance spectrum centre wavelength, by fiber grating after suitable encapsulation, can be made into specific fiber-optic grating sensor, fiber-optic grating sensor owing to thering is the electromagnetic interference of not being subject to, the feature such as volume is little, making is simple, wavelength sensitive, be widely used in remote optical sensing and optical communication field.
The technology that realizes at present fiber bragg grating center wavelength demodulation has following several conventionally, and they are spectral analysis techniques, the length scanning technology based on tunable optic filter, boundary filter technology, unbalanced M-Z interferometer demodulation techniques and coupling grating demodulation method etc.Spectral analysis technique is due to a large amount of mathematical computations of needs, and Wavelength demodulation speed is lower, cannot adapt to the measurement of large bandwidth signal; Unbalanced M-Z interferometer demodulation techniques are owing to existing zero drift problem to be only applicable at present the measurement of Dynamic Signal, optical filtering technology need to configure independent boundary filter and detector for each sensing grating, be not easy to the multiplexing of a plurality of grating sensors, and cost is higher; Wavelength resolution is high, measurement range is wide, the strong engineering widely that obtains of multiplexing capacity is applied because it has for length scanning technology based on tunable optic filter, but there is again based on the method grating demodulation system the problem that wavelength sweep rate is low in that sells in the market, therefore cannot meet the measurement demand of large Bandwidth Dynamic signal.
The reason of impact based on tunable optic filter grating demodulation systematic survey bandwidth mainly comprises following two aspects:
(1) restriction of the tunable speed of tunable optic filter self, in order to guarantee the Stability and dependability of laser instrument long-term work, the existing fiber laser tuned speed based on tunable optic filter all arrives a few kHz magnitudes at 1Hz conventionally.
(2) restriction of signals collecting and processing speed, keeping under the constant condition of scanning wavelength resolution, the switching rate of A/D and D/A is directly proportional to the wavelength sweep rate of tunable optic filter, and the data-handling capacity of demodulating system has limited the raising of A/D sample frequency, and under the constant condition of A/D sample frequency, can only reduce wavelength scanning range and wavelength resolution to improve wavelength sweep rate, but this can affect again multiplexing capacity and the demodulation accuracy of demodulating system.
Summary of the invention
Technology of the present invention is dealt with problems: overcome the deficiencies in the prior art, propose a kind of dynamic strain measurement instrument based on overlapping many gratings, to meet grating demodulation system based on the tunable optic filter measurement demand to large Bandwidth Dynamic strain signal.
The present invention solves the problems of the technologies described above adopted technical scheme: a kind of dynamic strain measurement instrument based on overlapping many gratings, a plurality of centre wavelengths that it is characterized in that utilizing overlapping inscription equally distributed sensor fibre grating 5 or adopt the method for many overlapping many gratings of parallel join to design the various stress based on fiber grating in wavelength scanning range, the sensor such as strain or impact shock, the same measurand of a plurality of fiber gratings that overlap perception simultaneously, the variable quantity of each raster center wavelength is directly proportional to the size of measurand, and under the effect of triangular wave D/A converter 11 and high-voltage drive 12, export continuous narrow linewidth wavelength based on wideband light source 1 and the grating demodulation system of tunable optic filter 2, output wavelength enters respectively overlapping many gratings 5 and etalon 6 after coupling mechanism 3, isolator 4 is for the reflected signal of isolation standard tool 6, the transmission spectrum of the reflectance spectrum of overlapping many gratings 5 and etalon 6 enters respectively photodetection 7, finally by Multi-path synchronous serial a/d converter 8 real-time synchronizations, gather the electric signal of photodetector 7 outputs, demodulation based on FPGA and control circuit 10 are for controlling work schedule and the output waveform of A/D converter 8 and D/A converter 11, receive in real time and process the signal of A/D converter 8 simultaneously, and by interface (PCI, USB or network interface), sending to computing machine 9 to be further processed the data of handling in real time, computing machine 9 mainly completes resolving and reconstruct of each sensing grating peak wavelength in overlapping many gratings of each length scanning cycle, demodulation based on FPGA and control circuit 10 can utilize peak extraction algorithm to calculate in real time the D/A controlling value of each length scanning overlapping many gratings and corresponding scanning voltage of each peak wavelength of etalon in the cycle, due to etalon each output peak value centre wavelength immobilize, and the peak wavelength of overlapping many grating outputs will move to long wave or shortwave direction under dynamic strain effect, computing machine 9 is by calculating the variable quantity of overlapping many gratings 5 each peak relative standard tool 6 each peak value centers, can calculate the variation of each sensing grating centre wavelength in overlapping many gratings, in addition because each sensing grating centre wavelength in overlapping many gratings 5 is uniformly-spaced uniformly distributed on frequency domain, and the output wavelength of tunable optic filter 2 is continuous linear distribution in time domain, so the calculation result of each sensing grating centre wavelength is also spacedly distributed continuously in time domain in overlapping many gratings, it is restructural dynamic strain information that the calculation result of each sensing grating centre wavelength in overlapping many gratings is combined by the scanning sequency of wavelength.
Because overlapping many gratings have the output of sensing grating response spectra in tunable optic filter forward and backward wave long scan process, in order to realize the object that uniformly-spaced gathers dynamic strain signal, each length scanning cycle needs to resolve the sensing grating response spectra of positive and negative both direction simultaneously, in order to realize the centre wavelength of each grating in overlapping many gratings, be uniformly distributed, the centre wavelength of each sensing grating in overlapping many gratings according to the following formula result of calculation is chosen simultaneously:
λ B [ i ] = λ S + [ i - 1 2 ] × λ E - λ S n - - - ( 1 )
In formula: λ b[i]be the centre wavelength of i sensing grating;
λ slength scanning starting point for tunable optic filter;
λ elength scanning terminal for tunable optic filter;
N is the total number of sensing grating.
Because overlapping many gratings can not guarantee that in manufacturing process the centre wavelength of each sensing grating is spacedly distributed completely in the wavelength scanning range of tunable optic filter, and each centre wavelength of sensing grating can occur to move around to shortwave and long wave direction under the effect of dynamic strain, the nonlinear sweep of tunable optic filter also can cause the unequal interval of sensing grating output spectra to distribute in addition, dynamic strain signal for correct reconstruct measurand, demodulation based on FPGA and control circuit (10) need to calculate in real time the peak of overlapping many gratings of each length scanning cycle and etalon, and result of calculation is sent to computing machine (9), result of calculation should comprise length scanning cycle n, the position t of each sensing grating centre wavelength in overlapping many gratings niand the peak of etalon, the centre wavelength corresponding due to the peak of etalon immobilizes, thereby computing machine (9) can calculate the variation delta λ of each sensing grating centre wavelength according to the position of each sensing grating centre wavelength in overlapping many gratings with respect to the change in location of etalon ni, then according to each sensing grating centre wavelength dynamic strain sensitivity coefficient k in overlapping many gratings ibe the dynamic strain information of restructural measurand, n scan period dynamic strain signal should be by reconstruct shown in following formula:
Δ ϵ n = { ( t n 1 , Δ λ n 1 k 1 ) , ( t n 2 , Δ λ n 2 k 2 ) , · · · , ( t ni , Δ λ ni k i ) } - - - ( 2 )
In formula: Δ ε nbe the dynamic strain information obtaining n scan period;
T nibe i sensing grating peak in n overlapping many gratings of scan period;
Δ λ niit is the center wavelength variation amount of i sensing grating in n overlapping many gratings of scan period;
K idynamic strain sensitivity coefficient for i sensing grating in overlapping many gratings.
Principle of the present invention: the overlapping many gratings that adopt in the present invention are that the phase mask by selecting with different centre wavelengths repeats to inscribe made at the same position of sensor fibre, it mainly has following characteristics: (1) synchronousness, the i.e. heat transfer agent of all sensing gratings that overlap perception simultaneously measurand; (2) compact conformation, because the grating of the sensing that is useful on is all scribed at the same sensitive position of sensor fibre.Measuring instrument based on these overlapping many gratings is mainly comprised of the overlapping many gratings for dynamic strain measurement and grating demodulation system two parts based on tunable optic filter and wideband light source, for overlapping many gratings of dynamic strain measurement, is on the same sensitive zones of same optical fiber, to repeat to inscribe a plurality of centre wavelength in wavelength scanning range and equally distributed fiber grating.Due in overlapping many preparing gratings process, grating of every increase all can have influence on centre wavelength and the reflectivity thereof of having inscribed grating, this inscription technological requirement to overlapping many gratings is higher, thereby limited the number that it can overlapping grating, in order further to improve the Measurement bandwidth of dynamic strain and to guarantee demodulation accuracy, can increase by the mode of many overlapping many gratings of parallel join the number of each length scanning cycle sensing grating, thereby realize more gratings object of sensing simultaneously.At each length scanning in the cycle, sensor based on above overlapping many gratings can uniformly-spaced obtain a plurality of sensing grating output spectras continuously, by the variation of each sensing grating centre wavelength of real-time resolving and according to after the time sequencing reconstruct of sensing grating output spectra appearance, can obtain more dynamic strain heat transfer agent, thereby can be in the measurement object that keeps realizing under the constant condition of tunable optic filter sweep speed large bandwidth signal, the present invention is without the sweep speed and the scanning step that improve tunable optic filter, and need not reduce the wavelength scanning range of tunable optic filter, thereby can on the basis of existing wavelength resolution and multiplexing capacity, realize sensing and the measurement of large Bandwidth Dynamic strain signal.
The present invention compared with prior art advantage is:
(1) the present invention adopt a plurality of centre wavelength in tunable optic filter wavelength scanning range uniformly-spaced equally distributed overlapping many gratings design dynamic strain sensing device, can effectively improve the existing Measurement bandwidth based on tunable optic filter grating demodulation system, have the advantages such as demodulating system wavelength resolution is high, measurement range is wide, multiplexing capacity is strong simultaneously concurrently.
(2) type of dynamic strain sensor that the present invention is based on overlapping many gratings can be linked together and be combined sensing by same optical fiber with the sensor of a plurality of employing monochromatic light grid design, thereby measurement demand when can meet existing low frequency small-signal and have again high frequency dynamic strain signal, range of application and the dirigibility that can effectively improve grating sensing.
Accompanying drawing explanation
Fig. 1 is that the dynamic strain measurement instrument system that the present invention is based on overlapping many gratings forms;
Fig. 2 the present invention is based on the overlapping dynamic strain measurement instrument demodulation principle of having inscribed two overlapping many gratings of centre wavelength, wherein: (a) be the sensing grating output spectra under dynamic strain effect of overlapping many gratings; (b) be the pectination output spectra of etalon; (c) be the scanning voltage of tunable optic filter;
The dynamic strain sensing principle of a plurality of sampling gratings of overlapping inscription on the single sensor fibre of Fig. 3;
Fig. 4 adopts two dynamic strain sensing principles that are carved with overlapping many grating fibers parallel join;
The overlapping many gratings of Fig. 5 the present invention are each cycle sensing grating reflectance spectrum under the sinusoidal dynamic strain effect of 100Hz;
The wavelength variations reflectance spectrum in sinusoidal dynamic strain each cycle of signal of 100Hz after Fig. 6 reconstruct of the present invention.
In figure: 1-width light source; 2-tunable optic filter; 3-fiber coupler; 4-isolator; The overlapping many gratings of 5-; 6-etalon; 7-photodetector; 8-A/D converter; 9-computing machine; Demodulation and the control circuit of 10-based on FPGA; 11-D/A converter; 12-high-voltage drive.
Embodiment
Below in conjunction with accompanying drawing and example, the present invention is described in further detail.
As shown in Figure 1, the dynamic strain measurement instrument based on overlapping many gratings mainly comprises wideband light source 1, tunable optic filter 2, fiber coupler 3, isolator 4, overlapping many gratings 5, etalon 6, photodetector 7, A/D converter 8, computing machine 9, the demodulation based on FPGA and control circuit 10, D/A converter 11 and high drive amplifying circuit 12, in figure, the optional use of wideband light source 1 has the power light source of higher gain flatness (band is wider than 40nm, wavelength coverage 1520nm ~ 1560nm, general power is greater than 10mW), wideband light source will become the laser of narrow linewidth after tunable optic filter 2, the output linewidth of selected tunable optic filter should be better than 0.01nm, to guarantee the demodulation accuracy of demodulating system, the narrow-linewidth laser that tunable optic filter 2 changes periodic output linearity under the effect of triangular voltage sweep voltage, the wavelength of narrow-linewidth laser periodically changes within the scope of 1520nm ~ 1560nm, triangular voltage sweep voltage is produced by D/A converter 11 and high-voltage drive 12 by the demodulation based on FPGA and control circuit 10, narrow linewidth output wavelength enters respectively overlapping many gratings 5 and etalon 6 after coupling mechanism 3, isolator 4 is for the reflected signal of isolation standard tool 6, through the reflection wave of the many gratings 5 of lap over and the transmitted wave of etalon 6, enter respectively photodetection 7, by A/D converter 8 real-time synchronizations, gather again the electric signal of photodetector 7 outputs, A/D converter 8 adopts multipath high-speed synchronous serial A/D, by this design, can effectively improve demodulation based on FPGA and the multi-channel parallel data-handling capacity of control circuit 10, reduce the demand of A/D conversion to the demodulation based on FPGA and control circuit 10 input and output pins, be convenient to the expansion of more demodulation passages.Demodulation based on FPGA and control circuit 10 are for controlling work schedule and the output waveform of A/D converter 8 and D/A converter 1, receive in real time and process the signal of A/D converter 8 simultaneously, finally by interface (PCI, USB or network interface), send to computing machine 9 to be further processed the data of handling in real time, computing machine 9 mainly completes resolving and reconstruct of each sensing grating peak wavelength in overlapping many gratings of each length scanning cycle, demodulation based on FPGA and control circuit 10 can utilize peak value to shift to an earlier date algorithm and calculate in real time each length scanning position of the corresponding scanning voltage of each peak wavelength in overlapping many gratings and etalon in the cycle, due to etalon each output peak value centre wavelength immobilize, and the peak wavelength of each sensing grating output will move to long wave or shortwave direction under dynamic strain effect in overlapping many gratings, computing machine 9 is by calculating the variable quantity of overlapping many gratings 5 each peak relative standard tool 6 each peak value centers, can calculate the variation of each overlapping many raster centers wavelength.
In Fig. 1, overlapping many gratings used need be determined the number of sensing grating and the interval of centre wavelength thereof according to the sweep speed of the requirement of dynamic strain measurement bandwidth and tunable optic filter, by formula (1), calculate again the centre wavelength of each grating in overlapping many gratings, finally by selecting corresponding preparing grating template to inscribe, because needing to carry out pretension before carrying out dynamic strain sensing, fix on overlapping many gratings, the centre wavelength of each grating will move to long wave direction simultaneously under the effect of pretension, thereby can relatively with bottom generation at the top of tunable optic filter triangular voltage sweep voltage further and zoom out, cause the unequal interval sampling of intersection, this problem can be eliminated by adjusting the scanning bias voltage of tunable optic filter.
As shown in Figure 2, demodulation principle for the dynamic strain measurement instrument based on overlapping many gratings, 4 sensing grating reflectance spectrums that Fig. 2 (a) exports within the single tunable optic filter length scanning cycle for overlapping many gratings of overlapping two centre wavelengths, wherein in forward scan and reverse scan process, produce respectively two sensing grating reflectance spectrums, the centre wavelength of sensing grating reflectance spectrum is corresponding with two sensing grating centre wavelengths in overlapping many gratings, because overlapping many gratings are inscribed in the identical region of sensor fibre, thereby there is close sensing sensitivity, the demodulation result of each scan period 4 sensing grating reflectance spectrum is consistent with the scope of dynamic strain, the time that just each sensing grating reflectance spectrum occurs is spacedly distributed successively, overlapping many gratings are under Dynamical stress effect, 4 sensing grating reflectance spectrums move the while to shortwave or long wave direction, the demodulation result of 4 sensing grating reflectance spectrums just can realize 4 times to the measurement of the dynamic strain signal of wavelength sweep rate after reconfiguring according to the order of formula (2) and time, thereby reach the object improving based on tunable optic filter grating demodulation systematic survey bandwidth.The pectination output spectra that Fig. 2 (b) is etalon, each pectination output spectra be spaced apart fixing 800pm, because the centre wavelength of each output spectra of etalon is subject to the impact of temperature very little, thereby can be used as reference wavelength, for the real-time dynamic calibration of overlapping many gratings, can effectively improve the demodulation accuracy of raster center wavelength.The scanning voltage that Fig. 2 (c) is tunable optic filter, can change the scope of tunable optic filter scanning wavelength by changing the bias voltage of sweep waveform and the amplitude of scanning voltage.
As shown in Figure 3, for select different phase mask plates to carry out the method for designing of a plurality of sensing gratings of overlapping inscription at the same position of sensor fibre, in overlapping many gratings inscription process, keep sensor fibre motionless, inscribed after first sensing grating, using the phase mask plate with different centre wavelengths instead inscribes for the second time, or directly select the phase mask plate with a plurality of sensing gratings to inscribe, to complete the inscription work of a plurality of sensing gratings, in overlapping many gratings, the reflectance spectrum centre wavelength of each sensing grating will move left and right under the tension and compression effect at dynamic stress, mobile result is as shown in the little figure in Fig. 2 (a).
As shown in Figure 4, for adopting two of parallel joins to be carved with the type of dynamic strain sensor method for designing of overlapping many gratings, this design can be reduced in the negative effect that on same optical fiber, a plurality of sensing gratings of overlapping inscription bring, to improve the number of sensing grating used in dynamic strain sensing, the reflectance spectrum signal of the overlapping many gratings of two-way can enter respectively independently photodetector, also can enter same photodetector by directional coupler and carry out signals collecting and processing, the sensing grating centre wavelength of using because all is all uniformly-spaced equally distributed in the wavelength scanning range of tunable optic filter, need be according to the requirement unified distribution of formula (1), there is not the overlapping problem of wavelength.
Embodiment 1
Mainly to overlapping inscription, having overlapping many gratings of two sensing gratings to realize 4 times of measuring methods to the dynamic sinusoidal strain signal of tunable optic filter sweep speed is below illustrated, Fig. 2 has provided the demodulation principle of the dynamic strain measurement instrument based on overlapping many gratings, the wavelength scanning range of tunable optic filter of take is example from 1535nm～1555nm, in overlapping many gratings, the centre wavelength of two sensing gratings can be chosen by formula (1), corresponding two sensing grating centre wavelengths are respectively 1540nm, 1550nm, the centre wavelength of each sensing grating is spaced apart 10nm, take tunable optic filter wavelength sweep rate as 500Hz be example, the dynamic strain sensing device that adopts overlapping many gratings design respectively can the same sensing point of double acquisition in the forward in each tunable optic filter length scanning cycle and reverse scan process measurand, add up to 4 times to single sensing grating the Measurement bandwidth of obtainable measurand, the actual information frequency acquisition that corresponding overlapping many gratings dynamic strain sense measuring device obtains should be 2kHz, the Measurement bandwidth of namely measured signal has improved 4 times, the output power spectrum of scanning wavelength and overlapping many gratings as shown in Figure 2, the demodulating system reflectance spectrum of overlapping many gratings and triangular voltage sweep voltage of tunable optic filter in forward and reverse scan process in figure, have been provided, wavelength scanning range is 1535nm～1555nm.Fig. 5 has provided the sinusoidal dynamic strain reflectance spectrum of 4 100Hzs of overlapping many gratings under 500Hz forward and the effect of reverse scan voltage, as shown in Figure 5,4 corresponding same tested dynamic strain signals of sensing grating output spectra, the peak of sensing grating output reflection spectrum presents periodic sinusoidal variations.Fig. 6 be in Fig. 54 sinusoidal dynamic strain reflectance spectrums by the later wavelength variations reflectance spectrum of formula (2) reconstruct, sensing grating output reflection spectrum has become 20 by 5 of single sensing grating, obtain 4 times of dynamic strain signals collecting to tunable optic filter sweep speed and counted, thereby effectively improved the Measurement bandwidth of dynamic strain signal.
In a word, the present invention is without selecting expensive high speed tunable optic filter and need not reducing wavelength scanning range, thereby can on the basis that does not affect original wavelength resolution and multiplexing capacity, realize the more measurement of high-bandwidth signals.The method can effectively improve the Measurement bandwidth based on tunable optic filter optical fiber grating sensing, can meet dynamic strain signal to high speed and high-precision while measurement demand.
Non-elaborated part of the present invention belongs to those skilled in the art's known technology.

Claims (6)

1. the dynamic strain measurement instrument based on overlapping many gratings, is characterized in that: comprise wideband light source (1), tunable optic filter (2), fiber coupler (3), isolator (4), overlapping many gratings (5), etalon (6), photodetector (7), A/D converter (8), computing machine (9), the demodulation based on FPGA and control circuit (10), D/A converter (11) and high drive amplifying circuit (12); Described overlapping many gratings (5) are to repeat to inscribe a plurality of sensing gratings with different centre wavelengths at sensor fibre the same area, and each centre wavelength of overlapping many gratings (5) is spacedly distributed tunable optic filter (2) wavelength scanning range planted agent; Demodulation based on FPGA and control circuit (10) are controlled wideband light source (1) by D/A converter (11) and high-voltage drive (12) and are exported continuous wavelength with tunable optic filter (2), and this output wavelength enters respectively overlapping many gratings (5) and etalon (6) after coupling mechanism (3); Isolator (4) is for the reflected signal of isolation standard tool (6); Through the reflection wave of the many gratings of lap over (5) and the transmitted wave of etalon (6), enter respectively photodetection (7), then deliver in the demodulation and control circuit (10) based on FPGA by the electric signal of A/D converter (8) real-time synchronization collection photodetector (7) output; Demodulation based on FPGA and control circuit (10) receive the signal of A/D converter (8) in real time, the peak of overlapping many gratings of each length scanning cycle (5) and etalon (6) in calculating signal, and result of calculation is sent to computing machine (9), the demodulation based on FPGA and control circuit (10) are for controlling work schedule and the output waveform of A/D converter (8) and D/A converter (11) simultaneously; Due to etalon (6) each output peak value centre wavelength immobilize, and the peak wavelength of overlapping many gratings (5) output will move to long wave or shortwave direction under dynamic strain effect, computing machine (9), by calculating the variable quantity of each peak of peak relative standard tool (6) of each sensing grating in overlapping many gratings (5), can calculate the variation of each sensing grating centre wavelength in overlapping many gratings (5); Each centre wavelength due to overlapping many gratings (5) is uniformly-spaced uniformly distributed on frequency domain in addition, and the output wavelength of tunable optic filter (2) is continuous linear distribution in time domain, the calculation result of each centre wavelength of overlapping many gratings (5) is also spacedly distributed continuously in time domain, and it is restructural dynamic strain information that the calculation result of each centre wavelength of overlapping many gratings (5) is combined by the scanning sequency of wavelength.
2. a kind of dynamic strain measurement instrument based on overlapping many gratings according to claim 1, is characterized in that: in described overlapping many gratings (5), a plurality of sensing gratings with different centre wavelengths are chosen according to the following formula:
λ B [ i ] = λ S + [ i - 1 2 ] × λ E - λ S n
In formula: λ b[i]be the centre wavelength of i sensing grating;
λ slength scanning starting point for tunable optic filter;
λ elength scanning terminal for tunable optic filter;
N is the total number of sensing grating.
3. a kind of dynamic strain measurement instrument based on overlapping many gratings according to claim 1, it is characterized in that: in order further to improve the Measurement bandwidth of dynamic strain, in described overlapping many gratings (5), also can pass through the production method of many overlapping many gratings of parallel join, be on every sensor fibre, all to have inscribed overlapping many gratings, the stiff end to dynamic strain measurement device by many sensor fibre parallel joins again, to realize more gratings for the object of the synchronous sensing of same measurand, but in many overlapping many gratings of parallel join, all sensing grating centre wavelength of using need be unified to choose, choosing method is:
λ B [ i ] = λ S + [ i - 1 2 ] × λ E - λ S n
In formula: λ b[i]be the centre wavelength of i sensing grating;
λ slength scanning starting point for tunable optic filter;
λ elength scanning terminal for tunable optic filter;
N is the total number of sensing grating.
4. a kind of dynamic strain measurement instrument based on overlapping many gratings according to claim 1, is characterized in that: the process of described computing machine (9) reconstruct dynamic strain information is: according to each sensing grating peak in overlapping many gratings, with respect to the change in location of etalon output peak value, calculate the variation delta λ of each sensing grating centre wavelength ni, then according to each sensing grating centre wavelength dynamic strain sensitivity coefficient k in overlapping many gratings ibe the dynamic strain information of restructural measurand, n scan period dynamic strain signal should be by reconstruct shown in following formula:
Δ ϵ n = { ( t n 1 , Δλ n 1 k 1 ) , ( t n 2 , Δλ n 2 k 2 ) , · · · , ( t ni , Δλ ni k i ) }
In formula: Δ ε nbe the dynamic strain information obtaining n scan period;
T nibe i sensing grating peaks of n overlapping many gratings of scan period;
Δ λ niit is the wavelength variations of i sensing grating of n overlapping many gratings of scan period;
K idynamic strain sensitivity coefficient for i sensing grating of overlapping many gratings.
5. a kind of dynamic strain measurement instrument based on overlapping many gratings according to claim 1, it is characterized in that: described A/D converter (8) adopts multipath high-speed synchronous serial A/D, by this multipath high-speed synchronous serial A/D, can effectively improve demodulation based on FPGA and the multi-channel parallel data-handling capacity of control circuit (10), reduce the demand of A/D conversion to the demodulation based on FPGA and control circuit (10) input and output pin, be convenient to the expansion of more demodulation passages.
6. a kind of dynamic strain measurement instrument based on overlapping many gratings according to claim 1, it is characterized in that: described tunable optic filter (2) adopts the mode of triangular wave or sinusoidal wave symmetrical scanning, and can change output wavelength by adjusting bias voltage and the peak-to-peak value scope of sweep waveform, so that the output wavelength of each sensing grating is spacedly distributed on frequency domain in overlapping many gratings (5) as far as possible.
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CN113124931B (en) * 2021-04-19 2022-08-05 全球能源互联网研究院有限公司 Method and device for improving power optical fiber state monitoring precision and storage medium

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6751367B2 (en) * 1999-04-02 2004-06-15 Ifos, Inc. Multiplexable fiber-optic strain sensor system with temperature compensation capability
CN100465601C (en) * 2007-04-19 2009-03-04 山东科技大学 Pressure-measuring fiber grating process and device
CN100491908C (en) * 2007-05-11 2009-05-27 上海大学 Sensing and visualized method for space flexible sail plate structure form
CN101221043A (en) * 2008-01-30 2008-07-16 中国科学院力学研究所 Method for measuring strain by optical fiber grating sensor at low temperature
CN101226051B (en) * 2008-01-30 2010-07-14 哈尔滨师范大学 Temperature self-compensation optical fiber/optical grating dynamic strain measurement method and system
CN101881633B (en) * 2010-04-06 2012-11-28 西安金和光学科技有限公司 Spring type high-precision optical fiber sensor based on optical fiber bending loss
CN101825434B (en) * 2010-04-28 2011-09-14 东北大学 Blazed fiber bragg grating demodulation-based micro-displacement sensor and detection method

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