CN109029271A - DFB array swept light source optical fiber frequency domain interfeerometry ranging system and method - Google Patents
DFB array swept light source optical fiber frequency domain interfeerometry ranging system and method Download PDFInfo
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- CN109029271A CN109029271A CN201811034265.8A CN201811034265A CN109029271A CN 109029271 A CN109029271 A CN 109029271A CN 201811034265 A CN201811034265 A CN 201811034265A CN 109029271 A CN109029271 A CN 109029271A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/026—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring distance between sensor and object
Abstract
The invention belongs to laser interference ranging technologies, for the contrast that can farthest improve interference signal, wide swept frequency range and good coherence are had both simultaneously, the present invention, DFB array swept light source optical fiber frequency domain interfeerometry ranging system and method, it is 20:80 broadband optical fiber coupler that the sweeping laser that DFB array swept light source generates, which initially enters splitting ratio, and 20% light separated enters the Mach Zehnder interferometer MZI of reference；In addition 80% light is 10:90 broadband optical fiber coupler by splitting ratio, and 10% enters the reference arm in two interfere arms；Other 90% enters test arm, test arm uses three end circulator structures, the sweeping laser is entered after fibre-optical probe by three end circulators is mapped to workpiece for measurement surface, it is collected from the reflected light on workpiece for measurement surface by same fibre-optical probe, enter the coupler for closing beam by three end circulators again, is interfered with reference light.Present invention is mainly applied to laser interference ranging occasions.
Description
Technical field
The invention belongs to laser interference ranging technology fields, interfere clearance measurement especially with regard to swept light source optical fiber frequency domain
Technology.Concretely relate to the optical fiber frequency domain interfeerometry ranging system based on DFB array swept light source.
Background technique
Many industry, science and military system need reliable high resolution method to measure distance, while having again stringent
Size sensor, power and complexity requirement.For example, the clearance measurement in the Grand Equipments such as engine, steam turbine is as shadow
One of the key parameter for ringing large size instrument runnability, in national product and national defence extensive application.As fired power generating unit
Core component, the axial gap of steam turbine are the thermal performance for improving supercritical pressure turbine and the operation for influencing supercritical pressure turbine
One of the key index of safety.Core working element of the movable vane piece as engine, its own running state parameter are especially dynamic
The variation of blade-tip clearance directly affects operating condition, working efficiency and the security performance of entire engine system.In addition, flying
Machine and other Grand Equipments etc. all to high intelligence, high performance manufacture development, assemble movement parts, the axis of rotor and stator
Effective control to distance etc. has high requirements, to guarantee that it assembles up to standard and operational safety.
Recent domestic has greatly developed contactless optical means to measure distance, and sensor is mounted on casing
On, the mechanical structure of this method non-destructive assay object, and can realize dynamic clearance real-time online measuring.Main method includes:
Optical time domain reflectometer (OTDR), optical frequency domain reflectometer (OFDR), white light interference technique, double frequency heterodyne interferometry, frequency sweep OCT method.
Optical time domain reflectometer (OTDR) is widely used in positioning fibre circuit and breakpoint and other exceptions in network.Method is simply easy
Row, but distributed sensing sensitivity is low, and measurement error is big, and general measure range can reach m grades of measurement spatial discrimination at km grades
Rate.Light frequency reflectometer (OFDR) is based on optical heterodyne detection method and light source linear frequency modulation, realizes high-acruracy survey.This method utilizes
Optical path difference is sought in the mixing for the coherent light that linear frequency modulation light source issues.With outstanding Detection of Weak Signals ability and good
Filtering performance, wide dynamic range have higher spatial resolution compared with optical time domain reflectometer (OTDR), in chromatographic technique,
Optical waveguide measurement, optical fiber measurement and fibre optical sensor field, have broad application prospects.Double frequency difference interference utilizes multi-wavelength
The advantages that interferometry realization large-scale absolute distance measurement, fast response time insensitive to light-intensity variation, high signal-to-noise ratio,
It is easily achieved high-acruracy survey, for range up to 100mm, resolving power is higher than 1nm, and precision is better than 10nm.The problem is that from root
The frequency stabilized carbon dioxide laser moderate dependent on spectral profile in sheet；Different frequency stabilized carbon dioxide laser, suitable for different measurement range and essence
Degree requires.White Light Interferometer has many advantages, such as pinpoint accuracy and quickly detection, but measurement range only reaches 1um~50um.It is applicable in
There are high light reflectivity, the absolute distance measurement with object specularly or diffusely in micron order, plane.Frequency sweep
The Method And Principle of OCT is similar with optical frequency domain reflectometer, is all based on the theory of light low coherence interference and Fourier transformation, main to apply
In mm grades of investigative range, um grades of measurement accuracy can reach.
But above-mentioned measuring method mainly also rests on laboratory stage at present, and rare develop to is adapted to industry now
Field on-line checking.Currently, mature method is mainly for the measurement range within 5mm, and between 10mm or so measuring range
Gap measures rare research, lacks technical support.How the precision scene of special operating environment under 10mm or so mid-gap is realized
Measurement blocks the live technique of dynamic measurement for breaking external gap, there is great meaning.
Summary of the invention
In order to overcome the deficiencies of the prior art, the present invention is directed to propose a kind of distance measuring method, the dress of new optical fiber frequency domain interference
It sets, can farthest improve the contrast of interference signal, while having both wide swept frequency range and good coherence, equipment is more
Step up to gather miniaturization.Thus the technical solution adopted by the present invention is that, DFB array swept light source optical fiber frequency domain interfeerometry ranging system,
It is 20:80 broadband optical fiber coupler, 20% light separated that the sweeping laser that DFB array swept light source generates, which initially enters splitting ratio,
Into the Mach Zehnder interferometer MZI of reference, the reference for the wave numbers such as the interference signal by the photodiode PD2 acquisition of MZI is
Clock signal, the signal reconstruction for later period main interferometer；In addition 80% light is the coupling of 10:90 broadband optical fiber by splitting ratio
Device, 10% enters the reference arm in two interfere arms, using the fibre delay line with electronic displacement platform, for adjusting the flat of interfere arm
Weighing apparatus, while the light intensity of two interference light of On-line matching；Other 90% enters test arm, and test arm uses three end circulator structures, institute
It states sweeping laser and is entered after fibre-optical probe by three end circulators and be mapped to workpiece for measurement surface, the reflected light quilt from workpiece for measurement surface
Same fibre-optical probe is collected, then enters the coupler for closing beam by three end circulators, is interfered with reference light；Interference light by
Indium gallium arsenic InGaAs PIN type photodetector carries out photoelectric conversion, by ADC after amplifier and filter amplify and filter
Analog-digital converter acquisition, wherein the clock signal of ADC acquisition is generated by the trigger signal clock of swept light source, and according to ginseng
The PD2 for examining MZI interferometer acquires clock signal of the interference signal come as signal reconstruction.
Further include computer, for doing Fast Fourier Transform (FFT) to obtained data, obtains distance value to be measured.
The swept light source of DFB array is C-band DFB array module laser light source, the current control circuit being made of FPGA
Plate provides electric current for each DFB array module to be scanned, and DFB array module is connected to be produced using the whole bandwidth of array
Raw equivalent scanning；Wherein, FPGA carries out the signal after zero passage sampling by comparing reference clock and MZI interference signal and generates PWM
Pulse width modulation error signal provides sweep current, while starting to export TTL triggering level letter according to each current scanning
Number, the clock signal for trigger data acquisition.
Fibre-optical probe uses self-focusing lens, and self-focusing lens plates anti-reflection film, avoids end face reflection light to the shadow of interference
It rings；Self-focusing lens is designed using short focus.
DFB array swept light source optical fiber frequency domain interfeerometry ranging method send the sweeping laser that DFB array swept light source generates
Entering splitting ratio is 20:80 broadband optical fiber coupler, and 20% light separated enters the Mach Zehnder interferometer MZI of reference, by MZI's
Photodiode PD2 acquisition interference signal be etc. wave numbers reference clock signal, the signal reconstruction for later period main interferometer；
In addition 80% light is 10:90 broadband optical fiber coupler by splitting ratio, and 10% enters the reference arm in two interfere arms, utilizes band
The fibre delay line of electricity driving displacement platform, for adjusting the balance of interfere arm, while the light intensity of two interference light of On-line matching；In addition
90% enters test arm, and test arm uses three end circulator structures, and the sweeping laser enters fibre-optical probe by three end circulators
After be mapped to workpiece for measurement surface, collected from the reflected light on workpiece for measurement surface by same fibre-optical probe, then by three end circulators into
Enter the coupler for closing beam, is interfered with reference light；Interference light is carried out by indium gallium arsenic InGaAs PIN type photodetector
Photoelectric conversion is acquired after amplifier and filter amplify and filter by ADC analog-digital converter, wherein the clock of ADC acquisition
Signal be generated by the trigger signal clock of swept light source, and according to reference to MZI interferometer PD2 acquisition come interference signal
Clock signal as signal reconstruction.
Collected data are handled as follows: distance of the fibre-optical probe end face apart from workpiece for measurement surface is d, probe
The workpiece surface reflected light of collection will be interfered with reference light, interference formula are as follows:
Wherein, L=2d, n are optical fibre refractivities, and λ (t) is swept light source length scanning
Function；To one specifically distance d, swept light source wavelength X is quickly scanned in the time domain, generate time domain interference signal,
FFT is done to this interference signal, the specific frequency f obtained is corresponded with distance d.
The features of the present invention and beneficial effect are:
(1) overcome common wavelength-swept laser source, such as micro electronmechanical (MEMS) outside cavity gas laser and electric variable semiconductor swash
Light device, the coherence length of laser source is very short (generally tens microns), and when ranging distance is more than coherence length, interference signal will
The shortcomings that degenerating rapidly.Exocoel scan-type swept light source is replaced using the swept light source based on DFB array, while having both wide frequency sweep
Range and good coherence, avoid interference with signal degradation and influence measurement accuracy.
(2) design of interference with common path instrument is overcome to be unable to two interfere arm light intensity of on-line control under measuring condition at the scene matched
Disadvantage, use are not total to optical path model, and the surface reflectivity that with the light intensity of two interference light of On-line matching, can adapt to measured workpiece is different
Actual conditions, farthest improve interference signal contrast.
(3) fibre-optical probe self-focusing lens directional light is overcome to be mapped to object under test surface collection backscattering light efficiency lower
The shortcomings that, it is designed using self-focusing lens short focus, allows hot spot more to concentrate and be mapped to surface to be measured, to improve reflected light to be measured
Collection efficiency.
(4) overcome complicated, the larger disadvantage of volume that receives interference signal device, using the single-photodetector of wide bandwidth,
It enormously simplifies and receives interference signal device, equipment miniaturization more compact reduces costs.
Detailed description of the invention:
Fig. 1 shows the range-measurement system block diagram of the optical fiber frequency domain interference of the invention based on DFB array swept light source.
Fig. 2 shows the functional block diagrams of DFB array swept light source.
Fig. 3 shows the design diagram of optical fiber self-focusing lens probe.
In Fig. 1: 1 is DFB array swept light source；2 be center wavelength be 1550nm wide-band coupler, splitting ratio 20/80；
Main interferometer is constituted by 3,4,5,6,7,8, the real-time acquisition of the interference light for being used to carry out carry distance information, in which: 3
It is 1550nm wide-band coupler, splitting ratio 10/90 for center wavelength；4 be three end optical fiber circulators；5 fibre-optical probes, end
The distance on face to workpiece for measurement surface is the distance of measurement；6 be the fibre delay line with electronic displacement platform；7 be that center wavelength is
1550nm wide-band coupler, for closing beam；8 be single-point InGaAs photodetector, response wave length 800-1700nm；9 be reference
Mach Zehnder interferometer (MZI), it is made of two three-dB couplers, and the optical path difference of two fiber turns is definite value, for generation etc.
The trigger signal of wave number interval sampling carries out signal reconstruction to the interference light signal of the carry distance information of main interferometer acquisition；
10 be ADC analog-digital converter, and 11 be FPGA, and 12 be USB chip, and 13 be computer.
Specific embodiment
The present invention provides a kind of distance measuring method of optical fiber frequency domain interference based on DFB array swept light source.It can overcome as
Lower disadvantage: (1) present invention can overcome common wavelength-swept laser source, and such as micro electronmechanical (MEMS) outside cavity gas laser and electricity are adjustable partly
Conductor laser, the coherence length of laser source is very short (generally tens microns), when ranging distance is more than coherence length, interference
The shortcomings that signal will degenerate rapidly.(2) present invention can overcome the design of interference with common path instrument at the scene cannot be online under measuring condition
The shortcomings that adjusting the matching of two interfere arm light intensity.(3) present invention can overcome fibre-optical probe self-focusing lens directional light to be mapped to work to be measured
The lower disadvantage of part surface collection backscattering light efficiency.(4) present invention can overcome that receive interference signal device complicated, volume compared with
Big disadvantage.
The present invention has the advantage that (1) replaces exocoel scan-type sweep light using the swept light source based on DFB array
Source, while wide swept frequency range and good coherence are had both, avoid interference with signal degradation；It (2), can be with using optical path model is not total to
The light intensity of two interference light of On-line matching, adapts to the different situations of the reflectivity of testee, farthest improves interference signal
Contrast.(3) fibre-optical probe is designed using self-focusing lens short focus, is allowed hot spot more to concentrate and is mapped to surface to be measured, thus
Improve the collection efficiency of reflected light to be measured.(4) single-photodetector for using wide bandwidth enormously simplifies and receives interference signal dress
It sets, makes equipment miniaturization more compact, reduce costs.
The present invention:
(1) a kind of optical fiber frequency domain interfeerometry ranging of swept light source based on distributed feedback laser (DFB) array is proposed
Method.Here we use C-band DFB array module as the laser source of relevant scanning wavelength ranging, customization current control electricity
Road plate provides customized current scanning for each DFB element, and the measurement feature from each element is connected to utilize battle array
The whole bandwidth (> 40nm) of column generates equivalent scanning.On the one hand, so that swept light source simultaneously have both wide swept frequency range and well
Coherence, avoiding interference with signal degradation influences measurement accuracy；On the other hand, different wave length is divided in time using swept light source
From can simplify acquisition device, it is no longer necessary to spectrometer, it is only necessary to which photodetector receives.
(2) the optical path model for proposing a kind of optical fiber frequency domain interfeerometry ranging, using Mach-Zenhder interferometer and
Reference arm and test arm are not total to the model of optical path.In actual field measurement, since the surface reflection of measured workpiece can not be changed
Rate, use are not total to optical path model, can be with the light intensity of two interference light of On-line matching, farthest to improve the comparison of interference signal
Degree.
(3) propose that a kind of reference arm and test arm are not total under conditions of optical path, the design scheme of fibre-optical probe.Fibre-optical probe
It is designed using self-focusing lens, on the one hand, self-focusing lens plates anti-reflection film, avoids influence of the end face reflection light to interference；Separately
On the one hand, it is designed using short focus, allows hot spot more to concentrate and be mapped to surface to be measured, to improve the collection effect of reflected light to be measured
Rate.
(4) a kind of Acquisition Circuit design of the single-photodetector of wide bandwidth is proposed.According to the sweep speed of swept light source,
And the distance range of measurement, the bandwidth requirement of photodetector is calculated, in the case where middle low frequency, using single photodetection
The detecting strategy of device.
The technical solution adopted by the present invention is that the optical fiber frequency domain interfeerometry ranging system of the swept light source based on DFB array, packet
It includes: (1) swept light source of DFB array
Laser source using C-band DFB array module as relevant scanning wavelength ranging, customization current control circuit plate are
Each DFB element provides customized current scanning, and the DFB array element that 12 line widths are 1MHz is connected to utilize array
Whole bandwidth 1528-1568nm (bandwidth of total 40nm) generate equivalent scanning, the step-length of scanning is that (C-band is 1GHz
0.8pm).(pulse is wide by comparing the signal generation PWM after the progress zero passage sampling of the interference signal of reference clock and MZI by FPGA
Degree modulation) error signal, for guaranteeing that current driving circuit plate generates the current scanning curve of stable setting, while according to every
Primary current scanning starts output TTL triggering level signal, can be used for the clock signal of trigger data acquisition.Two-arm is not total to light
The interferometer on road designs
Two interfere arms of Mach Zehnder interferometer are separated using coupler, wherein light of the reference arm with electronic displacement platform
Fine delay line, for adjusting the balance of interfere arm, while can be with the light intensity of two interference light of On-line matching；Test arm uses three end ring
Shape device, sweep light is entered after fibre-optical probe by circulator is mapped to workpiece for measurement surface, from the reflected light on workpiece for measurement surface by light
Fine probe collection, then the coupler for closing beam is entered by circulator, it is interfered with reference light.
(2) the self-focusing lens fibre-optical probe of short focus
The range determination of this system is by obtaining to received workpiece for measurement reflected light signal.Fibre-optical probe has both
Emit sweeping laser signal and receive the dual role of the signal after reflection, receives the back-scattering light of signal workpiece for measurement and miscellaneous
Scattered reflection optical signal.Wherein be tested end face reflection optical signal is influenced by its material reflectance and temperature parameter variation, to different
Object under test reflecting surface, the collection efficiency for improving back-scattering light are to improve the vital research of signal-to-noise ratio.For 10mm
Measuring range, the design uses the focal length of 7 ± 3mm, and the directional light for being compared to collimation is mapped to workpiece for measurement surface, short focus
Design, limited laser power is converged on the hot spot of very little, the collection efficiency of reflected light is improved.
(3) single-photodetector detects
The light intensity signal of acquisition is converted to electric signal by PIN photodiode, recycles I-V conversion circuit to current signal
Voltage signal is converted to, and carries out small-signal amplification.According to the sweep speed of swept light source, and measurement apart from range,
The bandwidth requirement for calculating photodetector, in the case where middle low frequency, using the detecting strategy of the single-photodetector in broadband.
In order to overcome the deficiencies of the prior art, accomplish that (1) overcomes common wavelength-swept laser source, outside such as micro electronmechanical (MEMS)
Cavity laser and electric tuneable semiconductor laser, the coherence length of laser source is very short (generally tens microns), when ranging distance
When more than coherence length, the shortcomings that interference signal will degenerate rapidly.(2) overcome interference with common path instrument design measuring condition at the scene
Under be unable to two interfere arm light intensity of on-line control matching the shortcomings that.(3) fibre-optical probe self-focusing lens directional light is overcome to be mapped to be measured
Workpiece surface collects the lower disadvantage of backscattering light efficiency.(4) overcome and receive interference signal device complexity, volume is biggish to be lacked
Point.
The present invention is implemented as follows:
(1) swept light source of DFB array is used
Laser source using C-band DFB array module as relevant scanning wavelength ranging, customization current control circuit plate are
Each DFB element provides customized current scanning, and the DFB array element that 12 line widths are 1MHz is connected to utilize array
Whole bandwidth 1528-1568nm (bandwidth of total 40nm) generate equivalent scanning, the step-length of scanning is that (C-band is 1GHz
0.8pm).(pulse is wide by comparing the signal generation PWM after the progress zero passage sampling of the interference signal of reference clock and MZI by FPGA
Degree modulation) error signal, for guaranteeing that current driving circuit plate generates the current scanning curve of stable setting, while according to every
Primary current scanning starts output TTL triggering level signal, can be used for the clock signal of trigger data acquisition.
(2) it is not total to the interferometer design of optical path using two-arm
Two interfere arms of Mach Zehnder interferometer are separated using coupler, wherein light of the reference arm with electronic displacement platform
Fine delay line, for adjusting the balance of interfere arm, while can be with the light intensity of two interference light of On-line matching；Test arm uses three end ring
Shape device, sweep light is entered after fibre-optical probe by circulator is mapped to workpiece for measurement surface, from the reflected light on workpiece for measurement surface by light
Fine probe collection, then the coupler for closing beam is entered by circulator, it is interfered with reference light.
(3) the self-focusing lens fibre-optical probe of short focus
The range determination of this system is by obtaining to received workpiece for measurement reflected light signal.Fibre-optical probe has both
Emit sweeping laser signal and receive the dual role of the signal after reflection, receives the back-scattering light of signal workpiece for measurement and miscellaneous
Scattered reflection optical signal.Wherein be tested end face reflection optical signal is influenced by its material reflectance and temperature parameter variation, to different
Object under test reflecting surface, the collection efficiency for improving back-scattering light are to improve the vital research of signal-to-noise ratio.For 10mm
Measuring range, the design uses the focal length of 7 ± 3mm, and the directional light for being compared to collimation is mapped to workpiece for measurement surface, short focus
Design, limited laser power is converged on the hot spot of very little, the collection efficiency of reflected light is improved.
(4) single-photodetector detects
The light intensity signal of acquisition is converted to electric signal by PIN photodiode, recycles I-V conversion circuit to current signal
Voltage signal is converted to, and carries out small-signal amplification.According to the sweep speed of swept light source, and measurement apart from range,
The bandwidth requirement for calculating photodetector, in the case where middle low frequency, using the detecting strategy of the single-photodetector in broadband.
It is described further with reference to the accompanying drawing with the experiment present invention.
In the present invention, laser of the swept light source using the DFB array of C-band, wave-length coverage 1528-1568nm is whole
The scanning speed of a wave band is 1KHz, and scanning step is 1GHz (being 0.8pm in C-band length), laser power 20mW.Simultaneously
The signal after zero passage sampling is carried out by comparing internal reference clock and MZI interference signal by the FPGA inside DFB, generates PWM
Error signal guarantees electric current driving plate sweep waveform, and exports corresponding Transistor-Transistor Logic level signal.
Further, sweeping laser initially enters broadband optical fiber coupler 2 (splitting ratio 20:80), and 20% enters reference
MZI, due to the interferometer optical path difference be definite value, by PD2 acquisition interference signal be etc. wave numbers reference clock signal, can
Signal reconstruction for later period main interferometer；In addition 80% enters main interferometer, is interfered by broadband optical fiber coupler 3 by two
Arm separates (splitting ratio 10:90), wherein 10% enters reference arm, using the fibre delay line with electronic displacement platform, for adjusting
The balance of interfere arm is saved, while can be with the light intensity of two interference light of On-line matching；Other 90% enters test arm, using three end ring shapes
Device, sweep light is entered after fibre-optical probe by circulator is mapped to workpiece for measurement surface, from the reflected light on workpiece for measurement surface by optical fiber
Probe collection, then the coupler for closing beam is entered by circulator, it is interfered with reference light.
Further, the range determination of this system is by obtaining to received workpiece for measurement reflected light signal.Light
Fibre probe has both transmitting sweeping laser signal and receives the dual role of the signal after reflection, receives signal workpiece for measurement backwards
Scatter light.In order to improve the collection efficiency of back-scattering light, for the measuring range of 10mm, the design uses the coke of 7 ± 3mm
Away from the directional light for being compared to collimation is mapped to workpiece for measurement surface, and the design of short focus converges in limited laser power very
On small hot spot, the collection efficiency of reflected light is improved.
Further, the light of different wave length is separated in time due to swept light source, using single InGaAs
The light intensity signal of acquisition is converted to electric signal by photodiode, and I-V conversion circuit is recycled to be converted to voltage to current signal
Signal, and carry out small-signal amplification.According to the sweep speed 1KHz of swept light source, and measurement apart from range 10mm,
In the case where middle low frequency, the bandwidth requirement 50MH or more of photodetector is selected, measurement request can be met.
Further, the reflected light of reference light and test arm is interfered when wide-band coupler exports.By InGaAs
PIN photoelectric detector carries out photoelectric conversion, is acquired after amplification and filtering by ADC analog-digital converter.Wherein ADC acquisition when
Clock signal is generated by the trigger signal clock of swept light source.And according to reference to MZI interferometer PD2 acquisition come interference letter
Clock signal number as signal reconstruction, obtained data are transferred on computer by USB chip and do Fast Fourier Transform (FFT)
(FFT), distance value to be measured (referring to the end face of fibre-optical probe to the distance on workpiece for measurement surface) is obtained.
Claims (5)
1. a kind of DFB array swept light source optical fiber frequency domain interfeerometry ranging system, characterized in that DFB array swept light source generated
It is 20:80 broadband optical fiber coupler that sweeping laser, which initially enters splitting ratio, and the Mach Zehnder that 20% light separated enters reference is dry
Interferometer MZI, by MZI photodiode PD2 acquire interference signal be etc. wave numbers reference clock signal, be used for later period trunk
The signal reconstruction of interferometer；In addition 80% light is 10:90 broadband optical fiber coupler by splitting ratio, and 10% enters in two interfere arms
Reference arm, using the fibre delay line with electronic displacement platform, for adjusting the balance of interfere arm, while On-line matching two is interfered
The light intensity of light；Other 90% enters test arm, and test arm uses three end circulator structures, and the sweeping laser is by three end circulators
It is mapped to workpiece for measurement surface after into fibre-optical probe, is collected from the reflected light on workpiece for measurement surface by same fibre-optical probe, then by
Three end circulators enter the coupler for closing beam, interfere with reference light；Interference light is by indium gallium arsenic InGaAs PIN type light
Electric explorer carries out photoelectric conversion, is acquired after amplifier and filter amplify and filter by ADC analog-digital converter, wherein
The clock signal of ADC acquisition is to be generated by the trigger signal clock of swept light source, and adopted according to the PD2 of reference MZI interferometer
Clock signal of the interference signal that collection comes as signal reconstruction.
2. DFB array swept light source optical fiber frequency domain interfeerometry ranging system as described in claim 1, characterized in that further include meter
Calculation machine obtains distance value to be measured for doing Fast Fourier Transform (FFT) to obtained data.
3. DFB array swept light source optical fiber frequency domain interfeerometry ranging system as described in claim 1, characterized in that DFB array
Swept light source is C-band DFB array module laser light source, and the current control circuit plate being made of FPGA is each DFB array mould
Block provides electric current to be scanned, and DFB array module is connected to generate equivalent scanning using the whole bandwidth of array；Wherein,
FPGA carries out the signal after zero passage sampling by comparing reference clock and MZI interference signal and generates pwm pulse width modulated error
Signal provides sweep current, while starting output TTL triggering level signal according to each current scanning, is used for trigger data
The clock signal of acquisition；Fibre-optical probe uses self-focusing lens, and self-focusing lens plates anti-reflection film, avoids end face reflection light to dry
The influence related to；Self-focusing lens is designed using short focus.
4. a kind of DFB array swept light source optical fiber frequency domain interfeerometry ranging method, characterized in that generate DFB array swept light source
Sweeping laser be sent into splitting ratio be 20:80 broadband optical fiber coupler, 20% light separated enter reference Mach Zehnder interference
Instrument MZI, by MZI photodiode PD2 acquire interference signal be etc. wave numbers reference clock signal, be used for later period main interference
The signal reconstruction of instrument；In addition 80% light is 10:90 broadband optical fiber coupler by splitting ratio, and 10% enters in two interfere arms
Reference arm, using the fibre delay line with electronic displacement platform, for adjusting the balance of interfere arm, while two interference light of On-line matching
Light intensity；Other 90% enter test arm, test arm use three end circulator structures, the sweeping laser by three end circulators into
It is mapped to workpiece for measurement surface after entering fibre-optical probe, is collected from the reflected light on workpiece for measurement surface by same fibre-optical probe, then by three
It holds circulator to enter the coupler for closing beam, is interfered with reference light；Interference light is by indium gallium arsenic InGaAs PIN type photoelectricity
Detector carries out photoelectric conversion, is acquired after amplifier and filter amplify and filter by ADC analog-digital converter, wherein ADC
The clock signal of acquisition be generated by the trigger signal clock of swept light source, and according to reference to MZI interferometer PD2 acquisition come
Clock signal of the interference signal as signal reconstruction.
5. DFB array swept light source optical fiber frequency domain interfeerometry ranging method as claimed in claim 4, characterized in that collecting
Data be handled as follows: distance of the fibre-optical probe end face apart from workpiece for measurement surface is d, and the workpiece surface of probe collection is anti-
Penetrating light and reference light will interfere, interference formula are as follows:
Wherein, L=2d, n are optical fibre refractivities, and λ (t) is swept light source length scanning letter
Number；To one specifically distance d, swept light source wavelength X is quickly scanned in the time domain, generate time domain interference signal, it is right
This interference signal is FFT, and the specific frequency f obtained is corresponded with distance d.
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| CN112255640B (en) * | 2020-09-11 | 2023-11-10 | 北京空间机电研究所 | Variable-frequency differential laser interference ranging device capable of adaptively adjusting light path |
| CN112946611A (en) * | 2021-02-04 | 2021-06-11 | 哈尔滨工业大学 | Sweep frequency nonlinear correction distance measurement method based on similar triangular interpolation sampling |
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