CN106643811B - Optical fiber multifrequency vibration detection and compensation system and method - Google Patents
Optical fiber multifrequency vibration detection and compensation system and method Download PDFInfo
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- CN106643811B CN106643811B CN201611173637.6A CN201611173637A CN106643811B CN 106643811 B CN106643811 B CN 106643811B CN 201611173637 A CN201611173637 A CN 201611173637A CN 106643811 B CN106643811 B CN 106643811B
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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
Abstract
The invention discloses multifrequency vibration detection and compensation systems in a kind of optical fiber, it is desirable to provide one kind can quickly, accurately measure and in compensated optical fiber multi-frequency method of the vibration to reduce the error of fiber geometries measurement instrument and the noise of optical fiber physical quantity sensor.It includes that module occurs for high Frequency Stabilized Lasers, vibration signal introduces and Wavelength division multiplexing module, difference interference optical path and vibration signal detecting module, Doppler signal acquisition process and four parts of compensating module, vibration signal in the optical fiber compensated is introduced into fiber-optic vibration and compensation system, vibration signal is collected by difference interference optical path, the multifrequency vibration signal in optical fiber being collected by the spectrum analysis processing of Doppler signal, vibration signal is transferred to by compensation system by the communication interface being connected with by compensation system, realize the compensation of optical fiber internal vibration signal.Big bandwidth can be achieved, fast vibration measurement and compensation in the optical fiber of multi-frequency.
Description
Technical field
The present invention relates to a kind of methods of the multifrequency vibration in measurement and compensated optical fiber, especially relate to optical fiber type laser
The noise reduction technology of multifrequency vibration compensation technology and partial fiber optic sensor in optical interference circuit.
Background technique
Optical fiber be widely used in the laser geometrics measurement instrument such as laser interferometer, laser radar and laser tracker and
In the physical quantities instruments such as temperature/humidity sensor, electric/magnetic field sensor and concentration sensor.In geometric measurement, optical fiber
As passing optical device, extraneous vibration and impact can change the shape of optical fiber and then change the length of optical path and light wave in optical fiber
Slight vibration in phase, big vibration and impact either long optical fibers can even change the quantity of interference fringe, this is to laser
Absolute interferometry and the precision of increment interferometry can all generate and seriously affect；And in the optical fiber measured to physical quantity
It is the main noise source of such sensor by fiber-optic vibration bring signal intensity in sensor.Existing passive type vibration
Isolation technology is to make a package to measuring device using vibration isolation table or vibration-absorbing material, and such method vibration isolation capability is limited, encounters
Judder or low-frequency vibration its isolation effect are with regard to very poor.The active vibration isolation technology being widely used at present is made pottery with piezoelectricity
Porcelain combines a series of photodetections and conditioning device to cooperate software realization, and not only realization is complicated, and cost is very high but also can only compensate
Amplitude is larger, the lower vibration of frequency or impact signal, is not able to satisfy 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 mixed multiple
The vibration of vibration frequency needs the technology of a kind of fiber-optic vibration that can detect multi-frequency simultaneously and real-time compensation in industry.
Summary of the invention
The shortcomings that the present invention overcomes the prior arts, it is roomy to provide a kind of vibration measuring band, and precision is high, can real-time compensation it is more
The fiber-optic vibration detection of kind vibration signal and compensation device.
In order to solve the above-mentioned technical problem, a kind of optical fiber multifrequency vibration detection and compensation system proposed by the present invention, comprising:
Module occurs for high Frequency Stabilized Lasers, for generating stable single-frequency laser, to mention to optical fiber multifrequency vibration detection with compensation system
For stable light source；Vibration signal introduces and Wavelength division multiplexing module, for that will be shaken by the optical signal of compensation system and optical fiber multifrequency
Dynamic detection is multiplexed by compensated optical fiber together with the optical signal of compensation system, by by after compensated optical fiber by the light of two frequencies
Signal color separation is simultaneously sent back to respectively by compensation system and optical fiber multifrequency vibration detection and compensation system；Heterodyne interference signal and vibration
Dynamic signal detection module, for the vibration signal introduced in optical fiber to 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 handling high speed
The vibration signal that photodetector detects chooses multiple effective Doppler frequency shifts caused by vibrating in signal, and to more
General Le frequency displacement is tracked, while the generation of new vibration signal and disappearing for old vibration signal are monitored in entire measurement period
It loses, converses the real-time displacement of vibration, vibration compensation is carried out to by compensation system by communication interface.
Further:
It is continuous-wave laser that module, which occurs, for the high Frequency Stabilized Lasers, for providing to fiber-optic vibration detection with compensation system
The outgoing light frequency of optical signal, the continuous-wave laser is different from by the light frequency of compensation system；
The vibration signal introduces and Wavelength division multiplexing module includes two 2 × 1 dual wavelength wavelength division multiplexers and is detected
Optical fiber, there are three pins, respectively two single-frequency pins and a double frequency pin for 2 × 1 dual wavelength wavelength division multiplexer；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 test single-frequency laser used in vibration signal with by compensation and be
The laser of system is multiplexed into an optical fiber, and output end is connected in the optical fiber compensated, and the 22 × 1st dual wavelength wavelength-division is multiple
It is reversely connected with device and is used, will be respectively connected at two-way simple signal to fiber-optic vibration by the double frequency output signal color separation in compensated optical fiber
Detection is with compensation system and by compensation system；
The difference interference optical path and vibration signal detecting module include the optical modulator of a fixed modulation frequency, one
2 × 1 fiber couplers, two optical fiber collimators, two reflecting mirrors, an Amici prism, a condenser lens and a high speed
Photodetector；Above-mentioned 2 × 1 fiber couplers, optical fiber collimator, reflecting mirror, Amici prism, condenser lens and high speed optoelectronic
The working frequency range of detector includes the transmitting optical frequency of 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
Crossing after optical modulator frequency modulation becomes spatial light through optical fiber collimator sending；In addition it is directly issued all the way by another optical fiber collimator
For spatial light, then recycles a reflecting mirror and Amici prism to build a Mach and increase Dare optical interference circuit；Above-mentioned two-way light exists
It is interfered on Amici prism, interference signal projects light onto high-speed photodetector through another reflecting mirror cooperation condenser lens
Photosurface on, so far complete vibration signal detection；
The Doppler signal acquisition process and compensating module include a High Speed Analog digital signal converter, a master
Chip and a communication interface are controlled, 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 microcontroller or Field Programmable Logic Array, 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 matches；The High Speed Analog digital signal converter and above-mentioned difference interference optical path and vibration signal are visited
The high-speed photodetector surveyed in module is connected, and vibration signal is sent into the master after being acquired by High Speed Analog digital signal converter
Chip is controlled, timesharing Fourier transformation is done in main control chip, transformed multiple pulses are acquired, with spectrum intensity and frequency interval
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 entire measurement period, obtain 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 converts out the displacement of multifrequency vibration, and the displacement of all frequency vibrations is accumulated as optical fiber internal vibration
Actual displacement；The vibration signal being converted to is given through communications interface transmission and does compensation data by the control unit of compensation system.
A kind of optical fiber multifrequency vibration detection and compensation method, utilize above-mentioned optical fiber multifrequency vibration detection and compensation system, institute
It states Doppler signal acquisition process and compensating module and carries out timesharing Fourier transformation using timesharing Fourier algorithm, take every time identical
The data of length do Fourier transformation, the Doppler frequency shift after finding out each Fourier transformation 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, f0It is used
The outgoing of high frequency stabilization continuous-wave laser light frequency, vibration velocity is found out using above formula, in the circulation taken out every time
The process of stating does Fourier transformation, until data are finished.
Further:
The Doppler signal acquisition process and compensating module spectrum intensity and frequency interval screening method determine effectively more
General Le frequency displacement, it may be assumed that compression pulse width takes peak less than limit value every frequency to limit value, all two pulsion phases after Fourier transformation
It is worth highest pulse, is denoted as effective arteries and veins higher than a certain proportion of pulse in frequency spectrum highest point for all in the frequency spectrum after Fourier transformation
It rushes, the modulating frequency that abscissa corresponding to effective impulse wave crest subtracts optical modulator is the corresponding Doppler's frequency of vibration signal
It moves；
Correlated frequency tracing tracking vibration signal in the Doppler signal acquisition process and compensating module threshold value
The variation of effective Doppler frequency shift, it may be assumed that corresponding to the effective impulse wave crest that spectrum intensity and frequency interval screening method determine
Given threshold around abscissa, the corresponding abscissa of the wave crest of effective impulse new after Fourier transformation falls in the threshold value next time
Interior, which is considered as the coherent pulse of pulse in the last time Fourier transformation threshold value, the corresponding abscissa of the wave crest of coherent pulse
Frequency is denoted as the correlated frequency that pulse wave crest in the last time Fourier transformation threshold value corresponds to abscissa frequency, 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.
The corresponding abscissa of the wave crest of pulse new after Fourier transformation falls in horizontal seat after last time Fourier transformation next time
Outside the threshold value for marking setting, it is determined as effective impulse through spectrum intensity and frequency interval screening method, is denoted as new vibration signal and produces
It is raw.
After there is no the corresponding abscissa of the wave crest of new pulse to fall in last time Fourier transformation after Fourier transformation next time
In the threshold value of abscissa setting, it is denoted as old vibration signal and disappears.
There is the corresponding abscissa of wave crest of multiple new pulses to fall in last time Fourier transformation after Fourier transformation next time
Afterwards in the threshold value of abscissa setting, the highest pulse of the corresponding intensity of wave crest is only taken to be denoted as coherent pulse.
Compared with prior art, the beneficial effects of the present invention are:
(1) bandwidth for the vibration signal that can be detected and compensate is very big, and frequency range is believed from direct current to High Speed Analog number
The half of number converter sampling rate；(2) a variety of vibration frequencies and real-time compensation in optical fiber can be detected；(3) it vibrates
The precision of detection and compensation is high.
Detailed description of the invention
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 and compensation system of the present invention.
Specific embodiment
Technical solution of the present invention is described in further detail in the following with reference to the drawings and specific embodiments, it is described specific
Embodiment is only explained the present invention, is not intended to limit the invention.
Detecting provided by the present invention for fiber-optic vibration with the device compensated includes four parts: mould occurs for high Frequency Stabilized Lasers
At block, vibration signal introducing and Wavelength division multiplexing module, difference interference optical path and vibration signal detecting module, Doppler signal acquisition
Reason and compensating module.This four part specific structures and function are as follows:
Module occurs for high Frequency Stabilized Lasers, is the fabulous high frequency stabilization continuous-wave laser 1 of frequency stability, for generating stabilization
Single-frequency laser, 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 1 is different from by the light frequency of compensation system.
Vibration signal introduces and Wavelength division multiplexing module, for will be by the optical signal of compensation system and optical fiber multifrequency vibration detection
Be multiplexed into together with the optical signal of compensation system by compensated optical fiber, by by after compensated optical fiber by the optical signal of two frequencies point
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
Introducing with Wavelength division multiplexing module includes two 2 × 1 dual wavelength wavelength division multiplexers and detected optical fiber 17,2 × 1 dual wavelength
There are three pins, respectively two single-frequency pins and a double frequency pin for wavelength division multiplexer；2 × 1 dual wavelength wavelength division multiplexer institutes
Two light frequencies supported are respectively by the light frequency of the light frequency of compensation system and 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 will test single-frequency laser used in vibration signal and be multiplexed by the laser of compensation system
In a piece optical fiber, output end is connected in the optical fiber 17 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 at two-way simple signal be respectively connected to fiber-optic vibration detect and compensate
System and by compensation system.
Heterodyne interference signal and vibration signal detecting module, for the vibration signal introduced in optical fiber to be passed through laser interference
The method of measurement detected, and heterodyne interference signal is detected by high-speed photodetector；As shown in figure 4, the difference interference light
Road and vibration signal detecting module include 4,2 × 1 fiber couplers 2, two of optical modulator of a fixed modulation frequency
Optical fiber collimator 3 and 7, two reflecting mirrors 8 and 10,9, condenser lenses 11 of an Amici prism and a high speed optoelectronic detection
Device 12；Above-mentioned 2 × 1 fiber couplers 2, optical fiber collimator 3 and 7, reflecting mirror 8 and 10, Amici prism 9,11 and of condenser lens
The working frequency range of high-speed photodetector 12 includes the transmitting optical frequency of continuous-wave laser 1；The high-speed photodetector 12
Detect the modulating frequency that the upper limit is higher than optical modulator 4；2 × 1 fiber coupler 2 divides the emergent light of continuous-wave laser 1
For two-way: wherein all the way by becoming spatial light through an optical fiber collimator 7 sending after 4 frequency modulation of optical modulator；In addition all the way directly
Being issued by another optical fiber collimator 3 is spatial light, then recycles a reflecting mirror 8 and Amici prism 9 to build a Mach and increases moral
That optical interference circuit；Above-mentioned two-way light interferes on Amici prism 9, and interference signal focuses saturating through the cooperation of another reflecting mirror 10
Mirror 11 projects light on the photosurface of high-speed photodetector 12, so far completes vibration signal detection.
Doppler signal acquisition process and compensating module, the vibration detected for reading and handling high-speed photodetector
Signal is chosen multiple effective Doppler frequency shifts caused by vibrating in signal, and is tracked to Doppler frequency shift, while
The disappearance of the generation of the new vibration signal of monitoring and old vibration signal, converses the real-time position of vibration in entire measurement period
It moves, vibration compensation is carried out to by compensation system by communication interface.As shown in figure 4, the Doppler signal acquisition process and benefit
Repaying module includes 13, main control chips 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 above-mentioned 4 modulating frequency of optical modulator
Times；The main control chip 14 is single-chip microcontroller or Field Programmable Logic Array, the single-chip microcontroller or field programmable logic
The clock frequency of array is higher than four times of above-mentioned 13 sample rate of High Speed Analog digital signal converter；The communication interface 15 and quilt
The control unit 16 of compensation system matches；The High Speed Analog digital signal converter 13 and above-mentioned difference interference optical path and vibration
High-speed photodetector 12 in dynamic signal detection module is connected, and vibration signal is acquired by High Speed Analog digital signal converter 13
After be sent into the main control chip 14, do timesharing Fourier transformation in main control chip 14, acquire transformed multiple pulses, 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 variation, meanwhile, the generation of new vibration signal and disappearing for old vibration signal are monitored in entire measurement period
Lose, obtain the time --- frequency characteristic, and then restore vibration signal；Effective Doppler frequency shift is extracted, and will be effective
The instantaneous velocity that Doppler frequency shift is converted into vibration further converts out the displacement of multifrequency vibration, the displacement of all frequency vibrations
It is accumulated as the actual displacement of optical fiber internal vibration；The vibration signal being converted to is transferred to through communication interface 15 by the control of compensation system
Unit 16 processed 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 issued
Single-frequency laser is divided into two-way light through fiber coupler 2, is all the way spatial light through an optical fiber collimator 3 outgoing, another way passes through light
Adjust device 4 to modulate a radiofrequency signal, later with to respectively enter the one 2 × 1st dual wavelength wavelength-division by the measurement light of compensation system multiple
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 compensates 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
A single-frequency output pin exports the detection optical frequency for being mixed with vibration signal respectively, and should return to by the optical frequency of compensation system.It will
Detection optical frequency becomes the difference interference light of spatial light input optical fibre vibration detection and compensation system by another optical fiber collimator 7
Road, it should return to by the optical frequency input of compensation system it is original by compensation system.The spatial light being emitted through the optical fiber collimator 3
It is reflected through a reflecting mirror 8, and the light being emitted through the optical fiber collimator 7 interferes on Amici prism 9, interference signal is through another
One reflecting mirror 10 is reflected into condenser lens 11, and condenser lens 11 focuses the light on the photosurface of high-speed photodetector 12.It is high
The optical signal detected is converted into electric signal by fast photodetector 12, is converted into counting through High Speed Analog digital signal converter 13
Word signal is sent into main control chip 14 and does signal processing.Treated, and signal is sent into through communication interface 15 by the control list of compensation system
Member 16 completes vibration compensation work.
In the present invention, Doppler signal acquisition process and compensating module use timesharing Fourier algorithm progress timesharing Fourier
The process of transformation, takes the data of equal length to do Fourier transformation every time, the Doppler after finding out each Fourier transformation respectively
Frequency displacement substitutes into formula 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, f0It is used
High frequency stabilization continuous-wave laser outgoing light frequency, find out vibration velocity using above formula, the data taken out every time followed
Ring above 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, does Fourier transformation to it.The frequency
Spectral intensity and frequency interval screening method refer to keeps pulse width small Spectrum compression pulse width after Fourier transformation first
In setting value (being denoted as δ), choose intensity peak (being denoted as A) in frequency spectrum, corresponding to abscissa frequency be denoted as fn1(first
Subscript n represents the number of timesharing Fourier transformation, and second subscript m represents time that Valid peak is chosen in each Fourier transformation
Sequence).The pulse in entire frequency spectrum is found, frequency is apart lower than limit value δ between all two pulses, only leaves and takes peak value of pulse
That highest pulse, after pulse are considered as secondary lobe, directly omit；The corresponding intensity in all pulse highest points is greater than or equal to
60%A's is all denoted as effective impulse, and pulse highest point corresponds to abscissa frequency and is denoted as fn2、fn3、fn4... other pulses are denoted as
Idler Pulse directly omits.Correlated frequency tracing refers to f in the threshold valuen1、fn2、fn3、fn4... it is set for center frequency
It sets abscissa threshold value (being denoted as σ), 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.Judge whether it is new with spectrum intensity and frequency interval screening method if falling in outside threshold value
Vibration occurs, and is not to give up；It is to have that the highest pulse of pulse strength is only taken if there are two or more coherent pulses
Imitate coherent pulse；If being fallen in threshold value without pulse wave crest, it is considered as old vibration signal and disappears.By above-mentioned selected effective cross
Coordinate value fn1、fn2、fn3、fn4... the modulating frequency that optical modulator is individually subtracted obtains the corresponding Doppler of each vibration signal
Frequency displacement fdnm, the Doppler frequency shift acquired is substituted 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 for the light that high frequency stabilization continuous-wave laser used is emitted.Record the speed
Degree, v1m、v2m……vnmCarry out the displacement that the corresponding vibration of each vibration frequency is just obtained about the integral of time, Suo Youzhen
The displacement of dynamic signal is accumulated as the actual displacement of optical fiber internal vibration, while mending through communication interface to by the result of compensation system
It repays.New effective impulse appearance or old effective impulse is allowed to disappear in entire measurement period, thus can completely detects
The emerging vibration into measurement process, can also reject the vibration stopped in time, avoid leakage compensation or overcompensation.It is above-mentioned
Method makes the random error that part variation is eliminated by compensation system, leaves behind a fixed systematic error, can be by most
Whole data processing disappears systematic error.
Next, successively access each N number of point of N~2N, 2N~3N ... in repeats the above process, until beyond sampling
Points, to complete the multifrequency vibration detection and compensation to optical fiber.
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, it may be assumed that compression pulse width after Fourier transformation
To limit value, all two pulsion phases take the highest pulse of peak value less than limit value every frequency, by the frequency after Fourier transformation
All in spectrum to be denoted as effective impulse higher than a certain proportion of pulse in frequency spectrum highest point, abscissa corresponding to effective impulse wave 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, the abscissa corresponding to effective impulse wave crest
Surrounding given threshold, the corresponding abscissa of the wave crest of effective impulse new after Fourier transformation is fallen in the threshold value next time, should
Pulse is considered as the coherent pulse of pulse in the last time Fourier transformation threshold value, the corresponding abscissa frequency note of the wave crest of coherent pulse
The correlated frequency of abscissa frequency, the corresponding vibration speed of correlated frequency are corresponded to for pulse wave crest in the last time Fourier transformation threshold value
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
It moves.
The corresponding abscissa of the wave crest of pulse new after Fourier transformation falls in horizontal seat after last time Fourier transformation next time
Outside the threshold value for marking setting, it is determined as effective impulse through spectrum intensity and frequency interval screening method, is denoted as new vibration signal and produces
It is raw.
After there is no the corresponding abscissa of the wave crest of new pulse to fall in last time Fourier transformation after Fourier transformation next time
In the threshold value of abscissa setting, it is denoted as old vibration signal and disappears.
There is the corresponding abscissa of wave crest of multiple new pulses to fall in last time Fourier transformation after Fourier transformation next time
Afterwards in the threshold value of abscissa setting, the highest pulse of the corresponding intensity of wave crest is only taken to be denoted as coherent pulse.
Embodiment:
As shown in figure 4, an optical fiber type Mach, which increases the reference arm of Dare interferometer, to be made of the optical fiber 17 of 1m long, measurement
Arm is spatial light, carries out the ranging of large scale laser interference in industry spot, light source used is 1550nm infrared laser, range accuracy
It is 1 μm.In actual use, the vibration of industry spot machine can be transmitted on the reference arm 17 of interferometer, reference arm optical fiber 17 every 1
μm vibration can all seriously affect measurement result.The process of 17 vibration compensation of reference arm optical fiber is carried out using the present invention are as follows:
Optical fiber multifrequency vibration detection and compensation system use the high frequency stabilized He-Ne laser 1 of 850nm wavelength, the light warp issued
Fiber coupler 2 divides for two-way, wherein entering wavelength division multiplexer 5 by the acousto-optic modulator 4 that modulating frequency is 40MHz all the way
850nm optical frequency entrance；The light that the 1550nm laser that the Mach compensated simultaneously increases Dare interferometer issues passes through wavelength-division multiplex
The 1550nm optical frequency entrance of device 5 converges with above-mentioned optical frequency, and the double frequency port through wavelength division multiplexer is input to this Mach increasing moral jointly
On the reference arm 17 of your interferometer.It introduces after extraneous vibration through reference arm 17 and is reversely connected with through another wavelength division multiplexer 6,
The signal of 850nm and 1550nm conveys back into optical fibers multifrequency vibration detection respectively and does with compensation system and the Mach compensated increasing Dare
Interferometer.The Mach compensated increases Dare interferometer other parts and remains unchanged；Optical fiber multifrequency vibration detection and compensation system it is outer
Poor optical interference circuit and vibration signal detecting module are also that Mach increases Dare interference structure, the high frequency stabilization He-Ne of above-mentioned 850nm wavelength
Laser 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
Collimator 7 is sequentially connected, and constitutes the measurement that Mach increases Dare interference structure in conjunction with the spatial light being emitted from optical fiber collimator 7
Arm；The another way of fiber coupler 2 is connected with optical fiber collimator 3, anti-in conjunction with the light and reflecting mirror 8 being emitted from optical fiber collimator 3
The light penetrated constitutes the reference arm that Mach increases Dare interference structure.The optical path of two-arm generates interference, interference letter on Amici prism 9
It number is converged to through reflecting mirror 10, condenser lens 11 on the photosurface of high-speed photodetector 12 and completes the detection of vibration signal.
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 microcontroller of 32 bit clock frequency 500MHz of block does main control chip.The data adopted first deposit the memory space to main control chip
In, first take preceding 1000 data points to do Fourier transformation (Short Time Fourier Transform, the corresponding sample of 1000 points with fft algorithm
Time is 8.3333ns), detect intensity peak occur in 41.05211MHz after doing compression processing to frequency spectrum, simultaneously only
Occurs another pulse wave crest on 43.28566MHz, intensity is the 80% of highest point, and two frequency phase-differences are more than
1MHz, so note two frequencies of 41.05211MHz and 43.28566MHz are effective frequency.Take 1MHz as abscissa threshold value, with
The wave crest of 1MHz before and after two frequencies of track 41.05211MHz and 43.28566MHz.The all wave crests of Fourier transformation next time go out
The frequency of present 40.05211MHz to 42.05211MHz is construed as and the identical vibration of generation 41.05MHz frequency for the first time
What dynamic source generated, as correlated frequency；The subsequent all wave crests of Fourier transformation appear in 42.28566MHz and arrive
The frequency of 44.28566MHz is construed as what vibration source identical as 43.28MHz frequency is generated for the first time generated, as related
Frequency.Two frequencies of obtained 41.05211MHz and 43.28566MHz are individually subtracted to the modulating frequency of acousto-optic modulator simultaneously
(40MHz) obtains Doppler frequency shift fd11=1.05211MHz and fd12=3.28566MHz.By fd11=1.05211MHz and fd12
Two frequencies of=3.28566MHz substitute into formula respectively
vnm=cfdnm/f0
Wherein f0It is the optical frequency of 850nm single-frequency laser, is 352.94118THz.The instantaneous vibration velocity acquired is
0.89429m/s and 2.79281m/s.
The 1001 to 2000th totally 1000 above-mentioned calculating of points repetition is taken, obtains two in 41.32788MHz and 43.85441MHz
A effective frequency, they and first time Fourier transformation 41.05211MHz and 43.28566MHz differ less than 1MHz respectively, recognize
The correlation that the 41.32788MHz that fixed second of Fourier transformation obtains is the 41.05211MHz that first time Fourier transformation obtains
Frequency；The 43.85441MHz that second of Fourier transformation obtains is the phase for the 43.28566MHz that first time Fourier transformation obtains
Close frequency.At this time still with correlated frequency tracing in threshold value, setting 1MHz is threshold value, after third time Fourier transformation
The corresponding frequency of pulse wave crest within the scope of 40.32788MHz~42.32788MHz regards as the related frequency of 41.32788MHz
Rate；The corresponding frequency of pulse wave crest within the scope of 42.85441MHz~44.85441MHz regards as the correlation of 43.85441MHz
Frequency.The modulating frequency 40MHz that two frequencies of 41.32788MHz and 43.85441MHz subtract acousto-optic modulator is obtained how general
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, obtain displacement caused by two this period of times of vibration source be respectively 12.25288nm and
36.38267nm direction of vibration is identical, the cumulative accumulation displacement for obtaining this period of time inner fiber internal vibration is 48.63655nm,
The data of compensation are transferred to SPI serial communication interface the Mach compensated to increase in the control unit of Dare interferometer.It takes again
2001 to 3000 totally 1000 points repeat the above process ... so using every 1000 points as cycling element, until being finished all numbers
According to.So that the Mach compensated is increased Dare interferometer because the random error that reference arm fiber-optic vibration introduces is compensated, only stays
The systematic error of next fixation can be eliminated in the calibration fitting stage by final data processing.
Time needed for single compensation is no more than 1 μ s, and the precision of compensation is not less than 10nm.
Although above in conjunction with attached drawing, invention has been described, and the invention is not limited to above-mentioned specific implementations
Mode, the above mentioned embodiment is only schematical, rather than restrictive, and those skilled in the art are at this
Under the enlightenment of invention, without deviating from the spirit of the invention, many variations can also be made, these belong to of the invention
Within protection.
Claims (7)
1. a kind of optical fiber multifrequency vibration detection and compensation system characterized by comprising
Module occurs for high Frequency Stabilized Lasers, for generating stable single-frequency laser, to be to optical fiber multifrequency vibration detection and compensation
System provides stable light source；
Vibration signal introducing and Wavelength division multiplexing module, for that by the optical signal of compensation system and optical fiber multifrequency vibration detection and will mend
The optical signal for repaying system is multiplexed on the optical fiber compensated together, by after the optical fiber that is compensated by the optical signal of two frequencies point
Color is simultaneously sent back to respectively by compensation system and optical fiber multifrequency vibration detection and compensation system；
Heterodyne interference signal and vibration signal detecting module, for the vibration signal introduced in optical fiber to be passed through laser interferometry
Method detected, heterodyne interference signal is detected by high-speed photodetector；
Doppler signal acquisition process and compensating module, the vibration letter detected for reading and handling high-speed photodetector
Number, multiple effective Doppler frequency shifts caused by vibrating in signal are chosen, and track to Doppler frequency shift, while whole
The disappearance of the generation of the new vibration signal of monitoring and old vibration signal, converses the real-time displacement of vibration in a measurement period,
Vibration compensation is carried out to by compensation system by communication interface.
2. optical fiber multifrequency vibration detection and compensation system according to claim 1, which is characterized in that
It is continuous-wave laser (1) that module, which occurs, for the high Frequency Stabilized Lasers, for optical fiber multifrequency vibration detection and compensation system
Optical signal is provided, the outgoing light frequency of the continuous-wave laser is different from by the light frequency of compensation system；
It includes two 2 × 1 dual wavelength wavelength division multiplexers and detected optical fiber that the vibration signal, which is introduced with Wavelength division multiplexing module,
(17), there are three pins, respectively two single-frequency pins and a double frequency pin for 2 × 1 dual wavelength wavelength division multiplexer；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 test single-frequency used in vibration signal and swash
It light and being multiplexed into an optical fiber by the laser of compensation system, output end is connected in the optical fiber (17) compensated, and the described 2nd 2
The reversal connection of × 1 dual wavelength wavelength division multiplexer (6) uses, and the double frequency output signal color separation in the optical fiber compensated is believed at two-way single-frequency
Number it is respectively connected to optical fiber multifrequency vibration detection and compensation system and by compensation system；
The heterodyne interference signal and vibration signal detecting module include the optical modulator (4) of a fixed modulation frequency, one 2
× 1 fiber coupler (2), two optical fiber collimators (3,7), two reflecting mirrors (8,10), an Amici prism (9), one it is poly-
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)；The detection upper limit of the high-speed photodetector (12) is higher than the modulating frequency of optical modulator (4)；
The emergent light of continuous-wave laser (1) is divided into two-way by 2 × 1 fiber coupler (2): wherein passing through optical modulator all the way
(4) issuing after frequency modulation through an optical fiber collimator (7) becomes spatial light；In addition it is directly issued all the way by another optical fiber collimator (3)
For spatial light, then recycles a reflecting mirror (8) and Amici prism (9) to build a Mach and increase Dare optical interference circuit；Above-mentioned two
Road light interferes on Amici prism (9), and interference signal throws light through another reflecting mirror (10) cooperation condenser lens (11)
It is mapped on the photosurface of high-speed photodetector (12), so far completes vibration signal detection；
The Doppler signal acquisition process and compensating module include a High Speed Analog digital signal converter (13), a master
Chip (14) and a communication interface (15) are controlled, 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 microcontroller or scene can compile
The clock frequency of journey logic array, 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) matches with by the control unit (16) of compensation system；The High Speed Analog digital signal
Converter (13) is connected with above-mentioned heterodyne interference signal with the high-speed photodetector (12) in vibration signal detecting module, vibration
Signal is sent into the main control chip (14) after being acquired by High Speed Analog digital signal converter (13), does in main control chip (14)
Timesharing Fourier transformation acquires transformed multiple pulses, determines effective Doppler with spectrum intensity and frequency interval screening method
Frequency displacement is changed with the Doppler frequency shift of correlated frequency tracing tracking vibration signal in threshold value, meanwhile, in entire measurement period
The generation of new vibration signal and the disappearance of old vibration signal are monitored, obtains the time --- frequency characteristic, and then restore vibration
Dynamic signal；Effective Doppler frequency shift is extracted, and effective Doppler frequency shift is converted into the instantaneous velocity of vibration again into one
Step converts out the displacement of multifrequency vibration, and the displacement of all frequency vibrations is accumulated as the actual displacement of optical fiber internal vibration；It is converted to
Vibration signal be transferred to through communication interface (15) compensation data done by the control unit (16) of compensation system.
3. a kind of optical fiber multifrequency vibration detection and compensation method, which is characterized in that shaken using optical fiber multifrequency as claimed in claim 2
Dynamic detection and compensation system, the Doppler signal acquisition process and compensating module use timesharing Fourier algorithm progress timesharing Fu
In leaf transformation, take the data of equal length to do Fourier transformation every time, Doppler after finding out each Fourier transformation respectively frequency
It moves, formula is substituted into according to Doppler frequency shift,
vnm=c × fdnm/f0
In formula, n represents the number of timesharing Fourier transformation, and m represents the order that Valid peak is chosen in each Fourier transformation, vnm
For vibration velocity, c is the speed of service (3 × 10 of light8m/s2), fdnmFor Doppler frequency shift, f0For high frequency stabilization continuous wave used
The frequency of the light of laser emitting finds out vibration velocity using above formula, is Fu for the datacycle above process taken out every time
In leaf transformation, until data are finished.
4. optical fiber multifrequency vibration detection and compensation method according to claim 3, which is characterized in that the Doppler signal is adopted
Collection processing and compensating module spectrum intensity and frequency interval screening method determine effective Doppler frequency shift, it may be assumed that after Fourier transformation
For compression pulse width to limit value, all two pulsion phases take the highest pulse of peak value every what frequency was less than limit value, and Fourier is become
It is all in frequency spectrum after changing to be higher than a certain proportion of pulse in frequency spectrum highest point and be denoted as effective impulse, corresponding to effective impulse wave crest
The modulating frequency that abscissa subtracts optical modulator is the corresponding Doppler frequency shift of vibration signal；
Correlated frequency tracing tracking vibration signal is effective in the Doppler signal acquisition process and compensating module threshold value
The variation of Doppler frequency shift, it may be assumed that the horizontal seat corresponding to the effective impulse wave crest that spectrum intensity and frequency interval screening method determine
Surrounding given threshold is marked, the corresponding abscissa of the wave crest of effective impulse new after Fourier transformation is fallen in the threshold value next time,
The new effective impulse is considered as the coherent pulse of pulse in the last time Fourier transformation threshold value, the corresponding cross of the wave crest of coherent pulse
Coordinate frequency is denoted as the correlated frequency that pulse wave crest in the last time Fourier transformation threshold value corresponds to abscissa frequency, 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 claim 4, which is characterized in that Fourier transformation next time
The corresponding abscissa of the wave crest of new pulse is fallen in outside the threshold value that abscissa is set after last time Fourier transformation afterwards, through spectrum intensity
It is determined as effective impulse with frequency interval screening method, is denoted as new vibration signal and generates.
6. optical fiber multifrequency vibration detection and compensation method according to claim 4, which is characterized in that Fourier transformation next time
The corresponding abscissa of the wave crest of not new pulse is fallen in the threshold value that abscissa is set after last time Fourier transformation afterwards, is denoted as old
Vibration signal disappear.
7. optical fiber multifrequency vibration detection and compensation method according to claim 4, which is characterized in that Fourier transformation next time
In the threshold value that abscissa is set after having the corresponding abscissa of wave crest of multiple new pulses to fall in last time Fourier transformation afterwards, only take
The highest pulse of the corresponding intensity of wave crest is denoted as coherent pulse.
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| CN109520609A (en) * | 2018-12-14 | 2019-03-26 | 天津大学 | A kind of measuring device of high speed rotor vibrational state |
| CN110361752B (en) * | 2019-07-03 | 2021-05-25 | 浙江大学 | Heterodyne interference-based moving object motion characteristic measurement method |
| WO2021128229A1 (en) * | 2019-12-27 | 2021-07-01 | 重庆康佳光电技术研究院有限公司 | Method and apparatus for screening out led chip to be transferred |
| CN111855031B (en) * | 2020-06-19 | 2021-10-15 | 太原理工大学 | Method for converting dual-frequency output of silicon resonance pressure sensor into single-frequency output |
| CN113483880A (en) * | 2021-08-17 | 2021-10-08 | 广东电网有限责任公司 | Vibration sensing system based on few-mode optical fiber |
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