CN106643811A - Optical fiber multi-frequency vibration detection and compensation system and method - Google Patents
Optical fiber multi-frequency vibration detection and compensation system and method Download PDFInfo
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- CN106643811A CN106643811A CN201611173637.6A CN201611173637A CN106643811A CN 106643811 A CN106643811 A CN 106643811A CN 201611173637 A CN201611173637 A CN 201611173637A CN 106643811 A CN106643811 A CN 106643811A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
- G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
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Abstract
The invention discloses an optical fiber multi-frequency vibration detection and compensation system and is aimed at providing a method for rapidly and accurately measuring and compensating multi-frequency vibration in an optical fiber so as to lower errors of an optical fiber geometric quantity measuring instrument and noise of an optical fiber physical quantity measurement sensor. The optical fiber multi-frequency vibration detection and compensation system comprises a high and stable frequency laser generation module, a vibration signal introducing and wavelength division multiplexing module, a heterodyne interference optical path and vibration signal detection module and a Doppler signal collection processing and compensating module; compensated vibration signals in the optical fiber are brought into an optical fiber vibration and compensation system, the vibration signals are collected via a heterodyne interference optical path, collected multi-frequency vibration signals in the optical fiber are processed via spectrum analysis of Doppler signals, the vibration signals are transmitted to a compensated system via a communication interface connected with the compensated system, and the vibration signals in the optical fiber can be compensated. Rapid measurement and compensation of vibration in a large bandwidth and multi-frequency optical fiber can be realized.
Description
Technical field
The present invention relates to a kind of method of measurement and many frequency vibrations in compensated optical fiber, especially relates to optical fiber type laser
The noise reduction technology of multifrequency vibration compensation technology and partial fiber optic sensor in optical interference circuit.
Background technology
Optical fiber be widely used in the laser geometric measurement instrument such as laser interferometer, laser radar and laser tracker and
In the physical quantity instruments such as temperature/humidity sensor, electric/magnetic field sensor and concentration sensor.In geometric measurement, optical fiber
Used as passing optical device, extraneous vibration and impact can change the shape of optical fiber and then change the length of light path and light wave in optical fiber
Phase place, big vibration and impact or the slight vibration in long optical fibers can even change the quantity of interference fringe, and this is to laser
Absolute interferometry and the precision of increment interferometry can all produce and have a strong impact on；And in the optical fiber measured to physical quantity
In sensor, the signal intensity brought by fiber-optic vibration is the main noise source of such sensor.Existing passive type vibration
Isolation technology is that measurement apparatus are done with a parcel using vibration isolation table or vibration-absorbing material, and such method vibration isolation capability is limited, runs into
Judder or its isolation effect of low-frequency vibration are just very poor.Active vibration isolation technology widely used at present is made pottery with piezoelectricity
Porcelain combines a series of photodetections and conditioning device coordinates software to realize, not only realizes complexity, and cost is very high and can only compensate
Amplitude is larger, the vibration that frequency is relatively low or impact signal, it is impossible to meet the demand of above-mentioned two aspects accurate measurement.It is prior
It is that optical fiber internal vibration signal is extremely complex, what is externally showed is frequently not the vibration of single-frequency, but has been mixed multiple
The vibration of vibration frequency, need in industry it is a kind of can and meanwhile detect multi-frequency fiber-optic vibration and real-Time Compensation technology.
The content of the invention
Instant invention overcomes the shortcoming of prior art, there is provided a kind of vibration measuring band is roomy, high precision, can real-Time Compensation it is many
Plant fiber-optic vibration detection and the compensation device of vibration signal.
In order to solve above-mentioned technical problem, a kind of optical fiber multifrequency vibration detection proposed by the present invention and compensation system, including：
There is module in high Frequency Stabilized Lasers, for producing stable single-frequency laser, so as to carry to optical fiber multifrequency vibration detection and compensation system
For stable light source；Vibration signal is introduced and Wavelength division multiplexing module, for by by many frequency vibrations of optical signal and optical fiber of compensation system
Dynamic detection is multiplexed into by compensated optical fiber together with the optical signal of compensation system, by the light of two frequencies after by compensated optical fiber
Signal color separation is simultaneously sent back to respectively by compensation system and optical fiber multifrequency vibration detection and compensation system；Heterodyne interference signal with shake
Dynamic signal detection module, for the vibration signal introduced in optical fiber to be detected by the method for laser interferometry, heterodyne
Interference signal is detected by high-speed photodetector；Doppler signal acquisition process and compensating module, for reading and are processed at a high speed
The vibration signal that photodetector is detected, chooses the multiple effective Doppler frequency shift caused by vibration in signal, and to many
The frequency displacement of general Le is tracked, while monitoring the generation of new vibration signal and disappearing for old vibration signal in whole measure the cycle
Lose, the real-time displacement of vibration is conversed, by communication interface to carrying out vibration compensation by compensation system.
Further：
It is continuous-wave laser that the high Frequency Stabilized Lasers occur module, for providing to fiber-optic vibration detection and compensation system
Optical signal, the outgoing light frequency of described continuous-wave laser is different from by the light frequency of compensation system；
The vibration signal introduces what is included two 2 × 1 dual wavelength wavelength division multiplexers with Wavelength division multiplexing module and be detected
Optical fiber, 2 × 1 dual wavelength wavelength division multiplexer has three pins, respectively two single-frequency pins and a double frequency pin；2×1
Two light frequencies that dual wavelength wavelength division multiplexer is supported are respectively by the light frequency of compensation system and the continuous-wave laser
Light frequency；Two 2 × 1 dual wavelength wavelength division multiplexers include the one 2 × 1st dual wavelength wavelength division multiplexer and the 22 × 1st dual wavelength
Wavelength division multiplexer, the one 2 × 1st dual wavelength wavelength division multiplexer will detect that the single-frequency laser used by vibration signal is with by compensation
The laser of system is multiplexed in an optical fiber, and output end is connected in the optical fiber for being compensated, and the 22 × 1st dual wavelength wavelength-division is answered
Used with device reversal connection, will be respectively connected to fiber-optic vibration into two-way simple signal by the double frequency output signal color separation in compensated optical fiber
Detection is with compensation system and by compensation system；
The optical modulator of the difference interference light path and vibration signal detecting module comprising a fixed modulation frequency, one
2 × 1 fiber couplers, two optical fiber collimators, two speculums, Amici prism, a condenser lens and a high speeds
Photodetector；Above-mentioned 2 × 1 fiber couplers, optical fiber collimator, speculum, Amici prism, condenser lens and high speed optoelectronic
Transmitting optical frequency of the working frequency range of detector comprising continuous-wave laser；The detection upper limit of the high-speed photodetector is higher than light
The modulating frequency of modulator；The emergent light of continuous-wave laser is divided into two-way by 2 × 1 fiber coupler：Wherein a-road-through
Cross the optical fiber collimators of Jing mono- after optical modulator frequency modulation and send and be changed into spatial light；Directly sent by another optical fiber collimator all the way in addition
For spatial light, then recycle a speculum and Amici prism to build a Mach and increase Dare optical interference circuit；Above-mentioned two-way light exists
Interfere on Amici prism, interference signal Jing another speculum coordinates condenser lens to project light onto high-speed photodetector
Photosurface on, so far complete vibration signal detection；
The Doppler signal acquisition process includes High Speed Analog digital signal converter, a master with compensating module
Control chip and a communication interface, the digit of the High Speed Analog digital signal converter is not less than 12, and sample rate is not less than
2 times of above-mentioned light modulator modulates frequency；The main control chip is single-chip microcomputer or FPGA, the master control
The clock frequency of chip is higher than four times of above-mentioned High Speed Analog digital signal converter sample rate；The communication interface with compensated
The control unit of system is engaged；The High Speed Analog digital signal converter is visited with above-mentioned difference interference light path and vibration signal
The high-speed photodetector surveyed in module is connected, and vibration signal sends into the master after being gathered by High Speed Analog digital signal converter
Control chip, does timesharing Fourier transformation, the multiple pulses after collection conversion, with spectrum intensity and frequency interval in main control chip
Screening method determines effective Doppler frequency shift, is changed with the Doppler frequency shift of correlated frequency tracing tracking vibration signal in threshold value,
Meanwhile, the generation of new vibration signal and the disappearance of old vibration signal are monitored in whole measure the cycle, draw the time ---
Frequency characteristic, and then restore vibration signal；Effective Doppler frequency shift is extracted, and effective Doppler frequency shift is converted into
The instantaneous velocity of vibration further changes out the displacement of many frequency vibrations, and the displacement of all frequency vibrations is accumulated as optical fiber internal vibration
Actual displacement；The vibration signal Jing communications interface transmissions being converted to are done compensation data by the control unit of compensation system.
A kind of optical fiber multifrequency vibration detection and compensation method, using above-mentioned optical fiber multifrequency vibration detection and compensation system, institute
State Doppler signal acquisition process carries out timesharing Fourier transformation with compensating module using timesharing Fourier algorithm, takes every time identical
The data of length do Fourier transformation, and the Doppler frequency shift after each Fourier transformation is found out respectively, according to Doppler frequency shift generation
Enter formula,
vnm=c × fdnm/f0
In formula, vnmFor vibration velocity, c is the speed of service (3 × 10 of light8m/s2), fdnmFor Doppler frequency shift, f0For used
High frequency stabilization continuous-wave laser outgoing light frequency, vibration velocity is obtained using above formula, in each circulation taken out
The process of stating does Fourier transformation, until data are finished.
Further：
The Doppler signal acquisition process determines effectively many with compensating module spectrum intensity and frequency interval screening method
General Le frequency displacement, i.e.,：To limit value, every two pulsion phases take peak to compression pulse width every frequency less than limit value after Fourier transformation
Value highest pulse, effective arteries and veins is designated as by all in the frequency spectrum after Fourier transformation higher than a certain proportion of pulse of frequency spectrum peak
Punching, the abscissa corresponding to effective impulse crest deducts the modulating frequency of optical modulator and is the corresponding Doppler's frequency of vibration signal
Move；
The Doppler signal acquisition process and correlated frequency tracing tracking vibration signal in compensating module threshold value
The effectively change of Doppler frequency shift, i.e.,：Corresponding to the effective impulse crest that spectrum intensity and frequency interval screening method determine
Given threshold around abscissa, next time the corresponding abscissa of the crest of effective impulse new after Fourier transformation fall in the threshold value
Interior, the pulse is considered as the coherent pulse of pulse in the last time Fourier transformation threshold value, the corresponding abscissa of crest of coherent pulse
Frequency is designated as the correlated frequency of pulse crest correspondence abscissa frequency in the last time Fourier transformation threshold value, and correlated frequency is corresponding
Integral reconstructors calculate a vibration signal between vibration velocity, and the displacement of all vibration signals is accumulated as the reality of optical fiber internal vibration
Border displacement.
Next time the corresponding abscissa of the crest of pulse new after Fourier transformation falls the horizontal seat after last time Fourier transformation
Outside the threshold value of mark setting, Jing spectrum intensities and frequency interval screening method are judged to effective impulse, are designated as new vibration signal and produce
It is raw.
The corresponding abscissa of crest next time without new pulse after Fourier transformation falls after last time Fourier transformation
In the threshold value of abscissa setting, it is designated as old vibration signal and disappears.
The corresponding abscissa of crest for having multiple new pulses after Fourier transformation next time falls in last time Fourier transformation
Afterwards in the threshold value of abscissa setting, only take the corresponding intensity highest pulse of crest and be designated as coherent pulse.
Compared with prior art, the invention has the beneficial effects as follows：
(1) bandwidth of the vibration signal that can be detected and compensate is very big, its frequency range numeral letter from direct current to High Speed Analog
/ 2nd of number converter sampling rate；(2) the various vibration frequencies and real-Time Compensation in optical fiber can be detected；(3) vibrate
Detection and the high precision for compensating.
Description of the drawings
Fig. 1 is the algorithm flow chart of Doppler signal acquisition process and compensating module；
Fig. 2 is spectrum intensity and frequency interval screening method algorithm flow chart；
Fig. 3 is correlated frequency tracing algorithm flow chart in threshold value；
Fig. 4 is the concrete structure diagram of optical fiber multifrequency vibration detection of the present invention and compensation system.
Specific embodiment
Below in conjunction with the accompanying drawings technical solution of the present invention is described in further detail with specific embodiment, described is concrete
Embodiment is only explained to the present invention, not to limit the present invention.
Detect provided by the present invention for fiber-optic vibration and include four parts with the device of compensation：There is mould in high Frequency Stabilized Lasers
At block, vibration signal introducing and Wavelength division multiplexing module, difference interference light path and vibration signal detecting module, Doppler signal collection
Reason and compensating module.This four part concrete structures and function are：
There is module in high Frequency Stabilized Lasers, be the fabulous high frequency stabilization continuous-wave laser 1 of frequency stability, stable for producing
Single-frequency laser, so as to provide stable light source (optical signal), the continuous wave to optical fiber multifrequency vibration detection and compensation system
The outgoing light frequency of laser instrument 1 is different from by the light frequency of compensation system.
Vibration signal is introduced and Wavelength division multiplexing module, for by by the optical signal of compensation system and optical fiber multifrequency vibration detection
It is multiplexed into together with the optical signal of compensation system by compensated optical fiber, divides the optical signal of two frequencies after by compensated optical fiber
Color is simultaneously sent back to respectively by compensation system and optical fiber multifrequency vibration detection and compensation system；As shown in figure 4, the vibration signal
Introduce includes two 2 × 1 dual wavelength wavelength division multiplexers and detected optical fiber 17,2 × 1 dual wavelength with Wavelength division multiplexing module
Wavelength division multiplexer has three pins, respectively two single-frequency pins and a double frequency pin；2 × 1 dual wavelength wavelength division multiplexer institutes
Two light frequencies supported are respectively by the light frequency of compensation system and the light frequency of the continuous-wave laser 1；Two 2 × 1
Dual wavelength wavelength division multiplexer includes the one 2 × 1st dual wavelength wavelength division multiplexer 5 and the 22 × 1st dual wavelength wavelength division multiplexer 6, described
One 2 × 1st dual wavelength wavelength division multiplexer 5 by detect vibration signal used by single-frequency laser be multiplexed into by the laser of compensation system
In a piece optical fiber, output end is connected in the optical fiber 17 for being compensated, and the 22 × 1st dual wavelength wavelength division multiplexer 6 reversal connection makes
With, will by the double frequency output signal color separation in compensated optical fiber into two-way simple signal be respectively connected to fiber-optic vibration detect with compensation
System and by compensation system.
Heterodyne interference signal and vibration signal detecting module, the vibration signal for will introduce in optical fiber passes through laser interference
The method of measurement is detected, and heterodyne interference signal is detected by high-speed photodetector；As shown in figure 4, the difference interference light
Road and 4,2 × 1 fiber coupler 2, two of optical modulator of vibration signal detecting module comprising a fixed modulation frequency
The 9, condenser lens 11 of the Amici prism of speculum 8 and 10, of optical fiber collimator 3 and 7, two and a high speed optoelectronic detection
Device 12；Above-mentioned 2 × 1 fiber couplers 2, optical fiber collimator 3 and 7, speculum 8 and 10, Amici prism 9, the and of condenser lens 11
Transmitting optical frequency of the working frequency range of high-speed photodetector 12 comprising continuous-wave laser 1；The high-speed photodetector 12
Modulating frequency of the detection upper limit higher than optical modulator 4；2 × 1 fiber coupler 2 divides the emergent light of continuous-wave laser 1
For two-way：Wherein lead up to the optical fiber collimators 7 of Jing mono- after the frequency modulation of optical modulator 4 and send and be changed into spatial light；It is direct all the way in addition
Sent as spatial light by another optical fiber collimator 3, then recycle a speculum 8 and Amici prism 9 to build a Mach and increase moral
That optical interference circuit；Above-mentioned two-way light is interfered on Amici prism 9, and another cooperation focusing of speculum 10 of interference signal Jing is saturating
Mirror 11 is projected light onto on the photosurface of high-speed photodetector 12, so far completes vibration signal detection.
Doppler signal acquisition process and compensating module, for reading and process the vibration that high-speed photodetector is detected
Signal, chooses the multiple effective Doppler frequency shift caused by vibration in signal, and Doppler frequency shift is tracked, while
The generation and the disappearance of old vibration signal of the new vibration signal of monitoring, converses the real-time position of vibration in whole measure the cycle
Move, by communication interface to carrying out vibration compensation by compensation system.As shown in figure 4, the Doppler signal acquisition process and benefit
Module is repaid comprising 13, main control chip 14 of a High Speed Analog digital signal converter and a communication interface 15, the height
The digit of fast analog and digital signal converter 13 is not less than 12, and sample rate is not less than the 2 of the modulating frequency of above-mentioned optical modulator 4
Times；The main control chip 14 is single-chip microcomputer or FPGA, the single-chip microcomputer or field programmable logic
The clock frequency of array is higher than four times of the above-mentioned sample rate of High Speed Analog digital signal converter 13；The communication interface 15 and quilt
The control unit 16 of compensation system is engaged；The High Speed Analog digital signal converter 13 and above-mentioned difference interference light path with shake
High-speed photodetector 12 in dynamic signal detection module is connected, and vibration signal is gathered by High Speed Analog digital signal converter 13
After send into the main control chip 14, do timesharing Fourier transformation in main control chip 14, the multiple pulses after collection conversion, with frequency
Spectral intensity and frequency interval screening method determine effective Doppler frequency shift, with correlated frequency tracing tracking vibration signal in threshold value
Doppler frequency shift changes, meanwhile, the generation of new vibration signal and disappearing for old vibration signal are monitored in whole measure the cycle
Lose, draw the time --- frequency characteristic, and then restore vibration signal；Effective Doppler frequency shift is extracted, and will be effective
Doppler frequency shift is converted into the displacement that the instantaneous velocity of vibration further changes out many frequency vibrations, the displacement of all frequency vibrations
It is accumulated as the actual displacement of optical fiber internal vibration；The vibration signal Jing communication interfaces 15 being converted to are transferred to by the control of compensation system
Unit processed 16 does compensation data.
As shown in figure 4, fiber-optic vibration detection of the present invention and compensation system, wherein what high frequency stabilization continuous-wave laser 1 sent
Single-frequency laser Jing fiber couplers 2 are divided into two-way light, and the outgoing of mono- optical fiber collimators of Jing 3 all the way is spatial light, separately leads up to light
Adjust device 4 modulate a radiofrequency signal, afterwards with by the measurement light of compensation system respectively enter the one 2 × 1st dual wavelength wavelength-division answer
With in two single-frequency pins of device 5.Two-way light is mixed into all the way from 2 × 1 dual wavelength wavelength division multiplexers 5 in wavelength division multiplexer
In the optical fiber 17 that double frequency pin is compensated needed for being linked into, the light exported from another pin of optical fiber 17 has been incorporated into vibration signal,
The signal is accessed from the double frequency pin of the 22 × 1st dual wavelength wavelength division multiplexer 6, from 6 liang of the 22 × 1st dual wavelength wavelength division multiplexer
Individual single-frequency output pin exports be mixed with the detection optical frequency of vibration signal respectively, and should return to by the optical frequency of compensation system.Will
Detection optical frequency becomes the difference interference light of spatial light input optical fibre vibration detection and compensation system through another optical fiber collimator 7
Road, it should return to be input into by the optical frequency of compensation system it is original by compensation system.The spatial light of the outgoing of optical fiber collimator 3 described in Jing
The speculums 8 of Jing mono- reflect, and the light of the outgoing of optical fiber collimator 7 is interfered on Amici prism 9 described in Jing, and interference signal Jing is another
One speculum 10 reflexes to condenser lens 11, and condenser lens 11 is focused the light on the photosurface of high-speed photodetector 12.It is high
The optical signal for detecting is converted into electric signal by fast photodetector 12, and Jing High Speed Analogs digital signal converter 13 is converted into number
Word signal sends into main control chip 14 and does signal transacting.Signal Jing communication interfaces 15 after process are sent into by the control list of compensation system
Unit 16 completes vibration compensation work.
In the present invention, Doppler signal acquisition process carries out timesharing Fourier with compensating module using timesharing Fourier algorithm
The flow process of conversion, the data that equal length is taken every time do Fourier transformation, and the Doppler after each Fourier transformation is found out respectively
Frequency displacement, according to Doppler frequency shift formula is substituted into,
vnm=c × fdnm/f0
In formula, vnmFor vibration velocity, c is the speed of service (3 × 10 of light8m/s2), fdnmFor Doppler frequency shift, f0For used
High frequency stabilization continuous-wave laser outgoing light frequency, vibration velocity is obtained using above formula, for each data taken out are followed
Ring said process seat Fourier transformation, until data are finished.
Fig. 1 shows the algorithm flow chart of Doppler signal acquisition process and compensating module in the present invention, High Speed Analog number
Word signal adapter collects a string of useful signals, first chooses the top n data of signal, and to it Fourier transformation is done.The frequency
Spectral intensity and frequency interval screening method are referred to and make pulse width little Spectrum compression pulse width after Fourier transformation first
In setting value (being designated as δ), intensity peak (being designated as A) in frequency spectrum is chosen, the abscissa frequency corresponding to it is designated as fn1(first
Subscript n represents the number of times of timesharing Fourier transformation, and second subscript m is represented chooses the secondary of Valid peak in each Fourier transformation
Sequence).The pulse in whole frequency spectrum is found, frequency only leaves and takes peak value of pulse at a distance of limit value δ is less than between every two pulses
Highest that pulse, its after pulse is considered as secondary lobe, directly omits；The corresponding intensity of every pulse peak is more than or equal to
60%A's is all designated as effective impulse, and its pulse peak correspondence abscissa frequency is designated as fn2、fn3、fn4... other pulses are designated as
Idler Pulse, directly omits.Correlated frequency tracing is referred to f in the threshold valuen1、fn2、fn3、fn4... centered on frequency set
Abscissa threshold value (being designated as σ) is put, the pulse after next Fourier transformation in threshold value σ can determine that as coherent pulse, impulse wave
The corresponding frequency in peak is correlated frequency.Determined whether with spectrum intensity and frequency interval screening method if falling outside threshold value new
Vibration occurs, and is not to give up；The pulse of pulse strength highest is only taken if there are two or more coherent pulses to have
Effect coherent pulse；If falling in threshold value without pulse crest, it is considered as old vibration signal and disappears.By above-mentioned selected effective horizontal stroke
Coordinate value fn1、fn2、fn3、fn4... the modulating frequency for being individually subtracted optical modulator draws the corresponding Doppler of each vibration signal
Frequency displacement fdnm, the Doppler frequency shift tried to achieve is substituted into into formula
vnm=c × fdnm/f0
Calculate the corresponding instantaneous vibration velocity of each vibration frequency, vnmFor vibration velocity, c be light the speed of service (3 ×
108m/s2), fdnmFor Doppler frequency shift, f0For the frequency of the light of high frequency stabilization continuous-wave laser outgoing used.Record the speed
Degree, v1m、v2m……vnmCarry out just obtaining the displacement of the corresponding vibration of each vibration frequency, Suo Youzhen with regard to the integration of time
The displacement of dynamic signal is accumulated as the actual displacement of optical fiber internal vibration, while Jing communication interfaces by the result of compensation system to being mended
Repay.Allow new effective impulse to occur in whole measure the cycle or old effective impulse disappears, thus can completely detection
The emerging vibration in measurement process, it is also possible to reject the vibration for having stopped in time, it is to avoid leakage compensation or overcompensation.It is above-mentioned
Method causes the random error that part change is eliminated by compensation system, leaves behind a fixed systematic error, can be by most
Whole data processing disappears systematic error.
Next, each N number of point of N～2N, 2N～3N ... repeats said process in fetching data successively, until beyond sampling
Points, so as to complete the multifrequency vibration detection to optical fiber with compensation.
Fig. 2 shows spectrum intensity and frequency interval screening method algorithm flow chart, the Doppler signal acquisition process with
Compensating module spectrum intensity and frequency interval screening method determine effective Doppler frequency shift, i.e.,：Compression pulse width after Fourier transformation
To limit value, every two pulsion phases take peak value highest pulse every frequency less than limit value, by the frequency after Fourier transformation
All in spectrum to be designated as effective impulse higher than a certain proportion of pulse of frequency spectrum peak, the abscissa corresponding to effective impulse crest subtracts
The modulating frequency for removing optical modulator is the corresponding Doppler frequency shift of vibration signal.
Fig. 3 shows correlated frequency tracing algorithm flow chart in threshold value, in the abscissa corresponding to effective impulse crest
Around given threshold, next time the corresponding abscissa of the crest of effective impulse new after Fourier transformation fall in the threshold value, should
Pulse is considered as the coherent pulse of pulse in the last time Fourier transformation threshold value, the corresponding abscissa frequency note of crest of coherent pulse
For the correlated frequency of pulse crest correspondence abscissa frequency in the last time Fourier transformation threshold value, the corresponding vibration speed of correlated frequency
Integral reconstructors calculate a vibration signal between degree, and the displacement of all vibration signals is accumulated as the actual bit of optical fiber internal vibration
Move.
Next time the corresponding abscissa of the crest of pulse new after Fourier transformation falls the horizontal seat after last time Fourier transformation
Outside the threshold value of mark setting, Jing spectrum intensities and frequency interval screening method are judged to effective impulse, are designated as new vibration signal and produce
It is raw.
The corresponding abscissa of crest next time without new pulse after Fourier transformation falls after last time Fourier transformation
In the threshold value of abscissa setting, it is designated as old vibration signal and disappears.
The corresponding abscissa of crest for having multiple new pulses after Fourier transformation next time falls in last time Fourier transformation
Afterwards in the threshold value of abscissa setting, only take the corresponding intensity highest pulse of crest and be designated as coherent pulse.
Embodiment：
As shown in figure 4, the reference arm of an optical fiber type Mach increasing Dare interferometer is made up of the optical fiber 17 of 1m length, measurement
Arm is spatial light, and in industry spot large scale laser interference range finding is carried out, and light source used is 1550nm infrared lasers, range accuracy
For 1 μm.When actually used, the vibration of industry spot machine can be transmitted on the reference arm 17 of interferometer, and reference arm optical fiber 17 is per 1
μm vibration can all have a strong impact on measurement result.The process that the vibration compensation of reference arm optical fiber 17 is carried out using the present invention is：
Optical fiber multifrequency vibration detection uses the high frequency stabilized He-Ne laser 1 of 850nm wavelength, the light Jing that it sends with compensation system
2 points of fiber coupler is two-way, wherein entering wavelength division multiplexer 5 for the acousto-optic modulator 4 of 40MHz through modulating frequency all the way
850nm optical frequency entrances；The light that the 1550nm laser instruments of the Mach increasing Dare interferometer for being compensated simultaneously send passes through wavelength-division multiplex
The 1550nm optical frequencies entrance of device 5 converges with above-mentioned optical frequency, and the double frequency port of common Jing wavelength division multiplexers is input to this Mach and increases moral
On the reference arm 17 of your interferometer.Jing reference arms 17 are introduced and use after extraneous vibration another reversal connection of wavelength division multiplexer 6 of Jing,
The signal of 850nm and 1550nm conveys respectively back into optical fibers multifrequency vibration detection and does with compensation system and the Mach for being compensated increasing Dare
Interferometer.The Mach for being compensated increases Dare interferometer other parts and keeps constant；Optical fiber multifrequency vibration detection is outer with compensation system
Difference optical interference circuit is also that Mach increases Dare interference structure, the high frequency stabilization He-Ne of above-mentioned 850nm wavelength with vibration signal detecting module
Laser instrument 1 and fiber coupler 2 all the way, acousto-optic modulator 4, wavelength division multiplexer 5, reference arm 17, wavelength division multiplexer 6 and optical fiber
The order of collimater 7 is connected, and with reference to the spatial light from the outgoing of optical fiber collimator 7 measurement that Mach increases Dare interference structure is constituted
Arm；Another road of fiber coupler 2 is connected with optical fiber collimator 3, anti-with reference to the light and speculum 8 from the outgoing of optical fiber collimator 3
The light penetrated constitutes the reference arm that Mach increases Dare interference structure.The light path of two-arm produces interference on Amici prism 9, interferes letter
Number reflected mirror 10, condenser lens 11 converge to the detection that vibration signal is completed on the photosurface of high-speed photodetector 12.
Signal after detection is sampled with a piece of 16 analog-digital converters with the sample rate of 120MS/s, uses one
The single-chip microcomputer of the bit clock frequency 500MHz of block 32 does main control chip.The data adopted first deposit the memory space of main control chip
In, first take front 1000 data point fft algorithms and do Fourier transformation (Short Time Fourier Transform, the corresponding sample of 1000 points
Time is 8.3333ns), frequency spectrum is done after compression is processed and detect and intensity peak occur in 41.05211MHz, while only
Occurs another pulse crest on 43.28566MHz, intensity is the 80% of peak, and two frequency phase-differences exceed
1MHz, so two frequencies of note 41.05211MHz and 43.28566MHz are effective frequency.1MHz is taken as abscissa threshold value, with
The crest of 1MHz before and after two frequencies of track 41.05211MHz and 43.28566MHz.The every crest of Fourier transformation next time goes out
Now the frequency of 40.05211MHz to 42.05211MHz is construed as being shaken with generation the identical of 41.05MHz frequencies first
What dynamic source produced, as correlated frequency；The every crest of follow-up Fourier transformation occurs in 42.28566MHz and arrives
The frequency of 44.28566MHz is construed as what vibration source identical with 43.28MHz frequencies are produced first was produced, as related
Frequency.Two frequencies of the 41.05211MHz for obtaining and 43.28566MHz are individually subtracted the modulating frequency of acousto-optic modulator simultaneously
(40MHz) Doppler frequency shift f is obtainedd11=1.05211MHz and fd12=3.28566MHz.By fd11=1.05211MHz and fd12
Two frequencies of=3.28566MHz substitute into respectively formula
vnm=cfdnm/f0
Wherein f0It is the optical frequency of 850nm single-frequency lasers, is 352.94118THz.The instantaneous vibration velocity tried to achieve is
0.89429m/s and 2.79281m/s.
Take the 1001 to 2000th totally 1000 points repeat above-mentioned calculating, obtain two in 41.32788MHz and 43.85441MHz
Individual effective frequency, they differ less than respectively 1MHz, recognize with first time Fourier transformation 41.05211MHz and 43.28566MHz
The 41.32788MHz that fixed second Fourier transformation is obtained is the correlation of the 41.05211MHz that first time Fourier transformation is obtained
Frequency；The 43.85441MHz that second Fourier transformation is obtained is the phase of the 43.28566MHz that first time Fourier transformation is obtained
Close frequency.Correlated frequency tracing in threshold value is now still used, setting 1MHz is threshold value, after third time Fourier transformation
The corresponding frequency of pulse crest in the range of 40.32788MHz～42.32788MHz regards as the related frequency of 41.32788MHz
Rate；The corresponding frequency of pulse crest in the range of 42.85441MHz～44.85441MHz regards as the correlation of 43.85441MHz
Frequency.How general modulating frequency 40MHz that two frequencies of 41.32788MHz and 43.85441MHz deduct acousto-optic modulator is obtained into
Strangle frequency displacement fd11=1.32788MHz and fd12=3.85441MHz.Still formula is substituted into
vnm=cfdnm/f0
Obtain another group of vibration velocity v21=2.05821m/s, v22=5.97434m/s.By v11、v21And v12、v22Respectively
Time is integrated, draw two vibration sources this displacements for causing for a period of time be respectively 12.25288nm and
36.38267nm, direction of vibration is identical, and the cumulative accumulation displacement for obtaining this period of time inner fiber internal vibration is 48.63655nm,
The data transfer of compensation is increased in the control unit of Dare interferometer to the Mach for being compensated with SPI serial communication interfaces.Take again
2001 to 3000 totally 1000 points repeat said process ... so with per 1000 points as cycling element, until being finished all numbers
According to.Finally make the Mach for being compensated increase Dare interferometer because the random error that reference arm fiber-optic vibration is introduced is compensated, only stay
The fixed systematic error of the next one can be eliminated the fitting stage is demarcated by final data processing.
Time needed for single compensation is less than 1 μ s, and the precision of compensation is not less than 10nm.
Although above in conjunction with accompanying drawing, invention has been described, the invention is not limited in above-mentioned being embodied as
Mode, above-mentioned specific embodiment is only schematic, rather than restricted, and one of ordinary skill in the art is at this
Under the enlightenment of invention, without deviating from the spirit of the invention, many variations can also be made, these belong to the present invention's
Within protection.
Claims (7)
1. a kind of optical fiber multifrequency vibration detection and compensation system, it is characterised in that include：
There is module in high Frequency Stabilized Lasers, for producing stable single-frequency laser, so as to give optical fiber multifrequency vibration detection with compensation system
System provides stable light source；
Vibration signal is introduced and Wavelength division multiplexing module, for by by the optical signal of compensation system and optical fiber multifrequency vibration detection and benefit
The optical signal for repaying system is multiplexed into together by compensated optical fiber, after by compensated optical fiber by the optical signal color separation of two frequencies simultaneously
Send back to respectively by compensation system and optical fiber multifrequency vibration detection and compensation system；
Heterodyne interference signal and vibration signal detecting module, the vibration signal for will introduce in optical fiber passes through laser interferometry
Method detect, heterodyne interference signal by high-speed photodetector detect；
Doppler signal acquisition process and compensating module, for reading and process the vibration letter that high-speed photodetector detects
Number, the multiple effective Doppler frequency shift caused by vibration in signal is chosen, and Doppler frequency shift is tracked, while whole
The generation of the new vibration signal of monitoring and the disappearance of old vibration signal, converse the real-time displacement of vibration in individual measure the cycle,
By communication interface to carrying out vibration compensation by compensation system.
2. optical fiber multifrequency vibration detection and compensation system according to claim 1, it is characterised in that
It is continuous-wave laser (1) that the high Frequency Stabilized Lasers occur module, for providing to fiber-optic vibration detection and compensation system
Optical signal, the outgoing light frequency of described continuous-wave laser is different from by the light frequency of compensation system；
The vibration signal is introduced includes two 2 × 1 dual wavelength wavelength division multiplexers and detected optical fiber with Wavelength division multiplexing module
(17), 2 × 1 dual wavelength wavelength division multiplexer has three pins, respectively two single-frequency pins and a double frequency pin；2×1
Two light frequencies that dual wavelength wavelength division multiplexer is supported are respectively by the light frequency of compensation system and the continuous-wave laser
(1) light frequency；Two 2 × 1 dual wavelength wavelength division multiplexers include the one 2 × 1st dual wavelength wavelength division multiplexer (5) and the 22 × 1st
Dual wavelength wavelength division multiplexer (6), the one 2 × 1st dual wavelength wavelength division multiplexer (5) will detect that the single-frequency used by vibration signal swashs
Light be multiplexed in an optical fiber by the laser of compensation system, output end is connected in the optical fiber (17) for being compensated, the described 2nd 2
× 1 dual wavelength wavelength division multiplexer (6) reversal connection is used, by by the double frequency output signal color separation in compensated optical fiber into two-way simple signal
Fiber-optic vibration detection is respectively connected to compensation system and by compensation system；
The optical modulator (4) of the difference interference light path and vibration signal detecting module comprising a fixed modulation frequency, one 2
× 1 fiber coupler (2), two optical fiber collimators (3,7), two speculums (8,10), Amici prism (9), one gather
Focus lens (11) and a high-speed photodetector (12)；It is above-mentioned 2 × 1 fiber couplers (2), optical fiber collimator (3,7), anti-
The working frequency range for penetrating mirror (8,10), Amici prism (9), condenser lens (11) and high-speed photodetector (12) swashs comprising continuous wave
The transmitting optical frequency of light device (1)；Modulating frequency of the detection upper limit of the high-speed photodetector (12) higher than optical modulator (4)；
The emergent light of continuous-wave laser (1) is divided into two-way by 2 × 1 fiber coupler (2)：Wherein lead up to optical modulator
(4) optical fiber collimators of Jing mono- (7) send and are changed into spatial light after frequency modulation；Directly sent by another optical fiber collimator (3) all the way in addition
For spatial light, then recycle a speculum (8) and Amici prism (9) to build a Mach and increase Dare optical interference circuit；Above-mentioned two
Road light is interfered on Amici prism (9), and interference signal Jing another speculum (10) coordinates condenser lens (11) to throw light
It is mapped on the photosurface of high-speed photodetector (12), so far completes vibration signal detection；
The Doppler signal acquisition process includes High Speed Analog digital signal converter (13), a master with compensating module
Control chip (14) and a communication interface (15), the digit of the High Speed Analog digital signal converter (13) is not less than 12,
Sample rate is not less than 2 times of above-mentioned optical modulator (4) modulating frequency；The main control chip (14) is that single-chip microcomputer or scene can compile
Journey logic array, the clock frequency of the main control chip (14) is higher than above-mentioned High Speed Analog digital signal converter (13) sample rate
Four times；The communication interface (15) is engaged with the control unit (16) by compensation system；The High Speed Analog data signal
Converter (13) is connected with above-mentioned difference interference light path with the high-speed photodetector (12) in vibration signal detecting module, vibration
Signal sends into the main control chip (14) after being gathered by High Speed Analog digital signal converter (13), does in main control chip (14)
Timesharing Fourier transformation, the multiple pulses after collection conversion, with spectrum intensity and frequency interval screening method effective Doppler is determined
Frequency displacement, is changed with the Doppler frequency shift of correlated frequency tracing tracking vibration signal in threshold value, meanwhile, in whole measure the cycle
The generation of the new vibration signal of monitoring and the disappearance of old vibration signal, draw the time --- frequency characteristic, and then restore and shake
Dynamic signal；Effective Doppler frequency shift is extracted, and the instantaneous velocity that effective Doppler frequency shift is converted into vibration is entered into again one
Step changes out the displacement of many frequency vibrations, and the displacement of all frequency vibrations is accumulated as the actual displacement of optical fiber internal vibration；It is converted to
Vibration signal Jing communication interfaces (15) be transferred to compensation data done by the control unit (16) of compensation system.
3. a kind of optical fiber multifrequency vibration detection and compensation method, it is characterised in that using many frequency vibrations of optical fiber as claimed in claim 2
Dynamic detection and compensation system, the Doppler signal acquisition process carries out timesharing Fu with compensating module using timesharing Fourier algorithm
In leaf transformation, the data that equal length is taken every time do Fourier transformation, and the frequency of the Doppler after each Fourier transformation is found out respectively
Move, formula substituted into according to Doppler frequency shift,
vnm=c × fdnm/f0
In formula, vnmFor vibration velocity, c is the speed of service (3 × 10 of light8m/s2), fdnmFor Doppler frequency shift, f0For height used
The frequency of the light of frequency stabilization continuous-wave laser outgoing, using above formula vibration velocity is obtained, in each datacycle taken out
The process of stating does Fourier transformation, until data are finished.
4. optical fiber multifrequency vibration detection and compensation method according to claims 3, it is characterised in that the Doppler signal
Acquisition process determines effective Doppler frequency shift with compensating module spectrum intensity and frequency interval screening method, i.e.,：Fourier transformation
Afterwards to limit value, every two pulsion phases take peak value highest pulse to compression pulse width every frequency less than limit value, by Fourier
It is all in frequency spectrum after conversion to be designated as effective impulse higher than a certain proportion of pulse of frequency spectrum peak, corresponding to effective impulse crest
Abscissa deduct the modulating frequency of optical modulator and be the corresponding Doppler frequency shift of vibration signal；
The Doppler signal acquisition process tracks the effective of vibration signal with correlated frequency tracing in compensating module threshold value
The change of Doppler frequency shift, i.e.,：In the horizontal seat corresponding to the effective impulse crest that spectrum intensity and frequency interval screening method determine
Surrounding given threshold is marked, next time the corresponding abscissa of the crest of effective impulse new after Fourier transformation falls in the threshold value,
The new effective impulse is considered as the coherent pulse of pulse in the last time Fourier transformation threshold value, the corresponding horizontal stroke of crest of coherent pulse
Coordinate frequency is designated as the correlated frequency of pulse crest correspondence abscissa frequency in the last time Fourier transformation threshold value, correlated frequency pair
Integral reconstructors calculate a vibration signal between the vibration velocity answered, and the displacement of all vibration signals is accumulated as optical fiber internal vibration
Actual displacement.
5. optical fiber multifrequency vibration detection and compensation method according to claims 4, it is characterised in that next time Fourier becomes
The corresponding abscissa of crest of new pulse falls after last time Fourier transformation outside the threshold value of abscissa setting after changing, and Jing frequency spectrums are strong
Degree and frequency interval screening method are judged to effective impulse, are designated as new vibration signal and produce.
6. optical fiber multifrequency vibration detection and compensation method according to claims 4, it is characterised in that next time Fourier becomes
The corresponding abscissa of crest without new pulse after changing falling in the threshold value of abscissa setting, be designated as after last time Fourier transformation
Old vibration signal disappears.
7. optical fiber multifrequency vibration detection and compensation method according to claims 4, it is characterised in that next time Fourier becomes
The corresponding abscissa of crest for having multiple new pulses after changing falls after last time Fourier transformation in the threshold value of abscissa setting, only
Take the corresponding intensity highest pulse of crest and be designated as coherent pulse.
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