CN110132138A - Double swept light source range-measurement systems and method based on cascade interferometer - Google Patents

Double swept light source range-measurement systems and method based on cascade interferometer Download PDF

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CN110132138A
CN110132138A CN201910399454.3A CN201910399454A CN110132138A CN 110132138 A CN110132138 A CN 110132138A CN 201910399454 A CN201910399454 A CN 201910399454A CN 110132138 A CN110132138 A CN 110132138A
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light source
interferometer
coupler
light
path difference
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CN110132138B (en
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曹建建
丁志华
方旭
马晓伟
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Ningbo Core Photoelectric Technology Co Ltd
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Ningbo Core Photoelectric Technology Co Ltd
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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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
    • G01B9/02007—Two or more frequencies or sources used for interferometric measurement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration

Abstract

The present invention relates to a kind of double swept light source range-measurement systems and method based on cascade interferometer, the coherent light that wherein the first swept light source and the second swept light source issue enters fiber coupler, main interferometer and cascade Mach-Zehnder interferometer are respectively enterd after being divided, coherent light into main interferometer part first passes through fiber coupler light splitting, a portion enters packet common path interference instrument with sample using fiber optical circulator, sample interference spectrum signal and the fiber coupler other end output of return enter the balance detection device of interference spectrum signal together, form interference spectrum signal, with the reference interference signal that is formed in cascade Mach-Zehnder interferometer synchronize be acquired.The light that second swept light source issues enters fiber coupler, and another part light after being divided enters light source frequency detection unit, and wavelength signals synchronize acquisition.The present invention can be improved the accuracy and reliability of measurement.

Description

Double swept light source range-measurement systems and method based on cascade interferometer
Technical field
The present invention relates to absolute distance measurement technical fields, more particularly to a kind of double sweep lights based on cascade interferometer Source range-measurement system and method.
Background technique
With high-end manufacture, aerospace manufacture, automobile manufacture and the development in the fields such as unmanned, range measurement is outstanding For important aspect.In currently used absolute distance dynamic measurement system and method, frequency sweep interferometry has measurement model Enclose the advantages that big, measurement accuracy is high.For the measurement accuracy for improving frequency sweep interferometry, lot of domestic and international colleges and universities and research institution Research report is carried out to this method.Chinese patent publication No. CN106226775A, data of publication of application on December 14th, 2016, title For " a kind of absolute distance dynamic measurement system and its measurement method based on swept frequency interferometer ", single-frequency laser is utilized in systems Device constitutes an additional heterodyne ineterferometer plus acousto-optic modulator and carries out real-time monitoring to the displacement of target, eliminates optical path The Doppler effect bring that variation introduces influences.But in this method, photoelectric device is more, structure is complicated, device volume is big, cost Height, reference interferometer are easily affected by the external environment, and introduce measurement error, and system requires the linearity of swept light source.
Summary of the invention
Technical problem to be solved by the invention is to provide a kind of double swept light source range-measurement systems based on cascade interferometer And method, it can be improved the accuracy and reliability of measurement.
The technical solution adopted by the present invention to solve the technical problems is: providing a kind of double frequency sweeps based on cascade interferometer Light source range-measurement system, including the first swept light source and the second swept light source, the light that first swept light source issues enter first The first input end of photo-coupler, the light that second swept light source issues enter the first input end of the second photo-coupler, institute The first output end for stating the second photo-coupler is connected with the second input terminal of the first photo-coupler, and the of first photo-coupler One output end is connected with the input terminal of cascade Mach-Zehnder interferometer, the output end and balance of the cascade Mach-Zehnder interferometer The input terminal of detector is connected, and the cascade Mach-Zehnder interferometer is used to form spectral signal all the way, and provides optical path difference and be d1The first reference signal, optical path difference d2The second reference signal, optical path difference d3Third reference signal and optical path difference be d4 The 4th reference signal；The second output terminal of first photo-coupler enters main interferometer, the sample arm of the main interferometer Road, including optical fiber circulator and collimator are total to reference arm, the of the first end of the optical fiber circulator and the first photo-coupler Two output ends are connected, and through the collimator, the reflecting mirror reflecting part inside the collimator is divided back the light for the light of second end The transmitted light of fine circulator, the collimator is incident upon on sample, and the reflecting part in collimator is divided and is mapped to detected sample Reflected light after product is converged to form interference, and the interference light of formation through the third end of fiber optical circulator and enters third fiber coupler Input terminal, two output ends of third fiber coupler are connected with two input terminals of the balanced detector, the balance The signal of detector detection carries out data acquisition and data processing through data collecting card and computer；Second photo-coupler Second output terminal is connected with the input terminal of the light source frequency detection unit based on pid algorithm；The light source frequency detection unit is used It is identified in the Frequency point to the second swept light source, and result is exported to data collecting card and computer and carries out data acquisition And data processing.
The cascade Mach-Zehnder interferometer includes the one 2 × 2nd broadband optical fiber coupler, the coupling of the 22 × 2nd broadband optical fiber Device, the 32 × 2nd broadband optical fiber coupler and the 42 × 2nd broadband optical fiber coupler, the first output of first photo-coupler It holds the light of output after the one 2 × 2nd broadband optical fiber coupler light splitting, is respectively l by length1And l2Fiber arm into Enter two input terminals of the 22 × 2nd broadband optical fiber coupler, light passes through the first output end of the 22 × 2nd broadband optical fiber coupler Into the input terminal of the 32 × 2nd broadband optical fiber coupler, respectively by for l after second is divided3And l4Fiber arm into Enter the input terminal of the 42 × 2nd broadband optical fiber coupler, the two-way output end of the 42 × 2nd broadband optical fiber coupler respectively with it is described The input terminal of balanced detector is connected；The second output terminal and photodetector phase of 22 × 2nd broadband optical fiber coupler Even.
The light source frequency detection unit includes collimator, beam expanding lens, spectroscope, the first detector, F-P cavity and the second spy Survey device, the light of the second output terminal of second photo-coupler enters the collimator, it is collimated enter the beam expanding lens into Row expands, and light a part after expanding enters first detector after spectroscope reflection, and another part is through described point The second detector is entered back into after entering F-P cavity after the transmission of light microscopic；The signal of first detector and the second detector is direct Data acquisition and data processing are carried out into the data collecting card and computer.
The measurement method of double swept light source range-measurement systems based on cascade interferometer, comprising the following steps:
It (1) is d by the optical path difference of cascade Mach-Zehnder interferometer using balanced detector1The first reference signal, light path Difference is d2The second reference signal, optical path difference d3Third reference signal and optical path difference be d4The 4th reference signal divided From；
(2) multiple and different Frequency points is obtained by light source frequency detection unit, by being fitted the smallest reference of optical path difference The phase of the corresponding interferometer of signal determines that the smallest reference signal of optical path difference is corresponding with the frequency curve of the second swept light source Interferometer integral multiple phase and small several times phase；
(3) it is measured simultaneously using the first swept light source and the second swept light source, is based on the smallest reference signal pair of optical path difference The integral multiple phase for the interferometer answered and small several times phase obtain the integral multiple phase for obtaining all interferometers by way of iteration Position and small several times phase；
(4) in the ω times sampling according toCalculate dynamic absolute distance value, wherein vωFor ω The frequency of second swept light source when secondary sampling, c are the light velocity,For the integral multiple phase of all interferometers,For all interference The small several times phase of instrument.
Beneficial effect
Due to the adoption of the above technical solution, compared with prior art, the present invention having the following advantages that and actively imitating Fruit: the present invention can carry out dynamic measurement to absolute distance, and ranging range is big, and precision reaches the precision of displacement interferometer measurement.This hair It is bright to provide the iterative calculation method of integral multiple phase and small several times phase, make distance that there is higher accuracy, reliability.This Invention provides the measurement method of reference frequency, and distance is made to have more stable length reference value, has distance higher heavy Renaturation, accuracy.
Detailed description of the invention
Fig. 1 is structural block diagram of the invention；
Fig. 2 is the structural block diagram of cascade Mach-Zehnder interferometer of the present invention；
Fig. 3 is the structural block diagram of light source frequency detection unit in the present invention；
Fig. 4 is the F-P cavity transmission spectrum of light source frequency detection unit in the present invention.
Specific embodiment
Present invention will be further explained below with reference to specific examples.It should be understood that these embodiments are merely to illustrate the present invention Rather than it limits the scope of the invention.In addition, it should also be understood that, after reading the content taught by the present invention, those skilled in the art Member can make various changes or modifications the present invention, and such equivalent forms equally fall within the application the appended claims and limited Range.
Embodiments of the present invention are related to a kind of double swept light source range-measurement systems based on cascade interferometer, as shown in Figure 1, Including the first swept light source 1 and the second swept light source 2, the light that first swept light source 1 issues enters the first photo-coupler 4 First input end, the light that second swept light source 2 issues enter the first input end of the second photo-coupler 3, second light First output end of coupler 3 is connected with the second input terminal of the first photo-coupler 4, and the first of first photo-coupler 4 is defeated Outlet is connected with the input terminal of cascade Mach-Zehnder interferometer 5, and the output end and balance of the cascade Mach-Zehnder interferometer 5 are visited The input terminal for surveying device 10 is connected, and the cascade Mach-Zehnder interferometer 5 is used to form spectral signal all the way, and provides optical path difference and be d1The first reference signal, optical path difference d2The second reference signal, optical path difference d3Third reference signal and optical path difference be d4 The 4th reference signal；The second output terminal of first photo-coupler 4 enters main interferometer, the sample arm of the main interferometer Road, including optical fiber circulator 6 and collimator 7, the first end of the optical fiber circulator 6 and the first photo-coupler 4 are total to reference arm Second output terminal be connected, through the collimator 7, the reflecting mirror reflecting part inside the collimator 7 is divided back for the light of second end The transmitted light of optical fiber circulator 6, the collimator 7 is incident upon on sample 8, and the reflecting part in collimator 7 is divided and is mapped to Reflected light after sample 8 is converged to form interference, and the interference light of formation through the third end of fiber optical circulator 6 and enters third light The input terminal of fine coupler 9, two input terminal phases of two output ends and the balanced detector 10 of third fiber coupler 9 Even, the signal that the balanced detector 10 detects carries out data acquisition and data processing through data collecting card 11 and computer 12； The second output terminal of second photo-coupler 3 is connected with the input terminal of the light source frequency detection unit 13 based on pid algorithm；Institute Light source frequency detection unit 13 is stated for identifying the Frequency point of the second swept light source, and result is exported to data and is acquired Card 11 and computer 12 carry out data acquisition and data processing.
The coherent light that first swept light source of the range-measurement system and the second swept light source issue enters fiber coupler, through dividing Main interferometer and cascade Mach-Zehnder interferometer are respectively enterd after light, the coherent light into main interferometer part first passes through optical fiber coupling Clutch light splitting, a portion enter packet common path interference instrument with sample, the sample interference light of return using fiber optical circulator Spectrum signal and the output of the fiber coupler other end enter the balance detection device of interference spectrum signal together, form interference spectrum letter Number, with the reference interference signal that is formed in cascade Mach-Zehnder interferometer synchronize be acquired.The light that second swept light source issues Into fiber coupler, another part light after being divided enters light source frequency detection unit, and wavelength signals synchronize acquisition.
As shown in Fig. 2, the cascade Mach-Zehnder interferometer 5 include the one 2 × 2nd broadband optical fiber coupler the 14, the 2nd 2 × 2 broadband optical fiber couplers 15, the 32 × 2nd broadband optical fiber coupler 17 and the 42 × 2nd broadband optical fiber coupler 18, described first The light of the first output end output of photo-coupler 4 passes through respectively after the one 2 × 2nd broadband optical fiber coupler 14 light splitting Length is l1And l2Fiber arm enter two input terminals of the 22 × 2nd broadband optical fiber coupler 15, light is by the 22 × 2nd wide The first output end with fiber coupler 15 enters the input terminal of the 32 × 2nd broadband optical fiber coupler 17, is divided by second Afterwards respectively by for l3And l4Fiber arm enter the 42 × 2nd broadband optical fiber coupler 18 input terminal, the 42 × 2nd broadband light The two-way output end of fine coupler 18 is connected with the input terminal of the balanced detector 10 respectively；22 × 2nd broadband optical fiber The second output terminal of coupler 15 is connected with photodetector 16.
As shown in figure 3, the light source frequency detection unit 13 includes collimator 19, beam expanding lens 20, the spy of spectroscope 21, first Device 22, F-P cavity 23 and the second detector 24 are surveyed, the light of the second output terminal of second photo-coupler 3 enters the collimator 19, collimated to be expanded into the beam expanding lens 20, light a part after expanding enters after the spectroscope 21 reflection First detector 22, another part enter back into the second detector after entering F-P cavity 23 after the transmission of the spectroscope 21 24；The signal of first detector 22 and the second detector 24 is directly entered the data collecting card and computer carries out data Acquisition and data processing.It is as shown in Figure 4 that F-P cavity transmits spectral line.
When being measured using double swept light source range-measurement systems based on cascade interferometer, the first swept light source and second Swept light source needs to have the following conditions: the first swept light source 1 is contrary with the frequency sweep of the second swept light source 2, such as first The frequency of swept light source 1 is ascending, then the frequency of the second swept light source 2 is descending.First swept light source 1 and the second frequency sweep Light source 2 has that component frequency is equal in frequency sweep, that is, has identical wavelength points.The sweep velocity of first swept light source 1 is more than second 2 times of the sweep velocity of swept light source 2.The sweep velocity of first swept light source 1 and the second swept light source 2 is more than 100kHz. The coherence distance of first swept light source 1 and the second swept light source 2 in a vacuum is greater than 1 meter.
Whole system is controlled the initial time of measurement time started, scan frequency, the second sweep light by the second swept light source 2 Source 2 issues trigger signal, after the first swept light source 1 and data collecting card 11 receive trigger signal, start respectively scan frequency and Acquire signal.
Frequency discriminator makees frequency discriminator using F-P cavity.When concrete application, F-P cavity is placed in semiconductor temperature module, temperature control system System uses PID algorithm control circuit；Function when first detector 22 and the second detector 24 are for eliminating light source tuning Rate, which fluctuates bring, to be influenced.
Fourier transform and Windowed filtering processing are carried out by the spectral interference striped to cascade Mach-Zehnder interferometer, is obtained It is d to optical path difference1、d2、d3And d4Interference signal spatial spectrum, using inverse Fourier transform obtain optical path difference be d1Reference Interference signal 1, optical path difference d2Reference interference signal 2, optical path difference d3Reference interference signal 3, optical path difference d4Reference Interference signal 4.It is split by the optical path to cascade Mach-Zehnder interferometer, obtains optical path difference d1Spectral interference striped, Fourier transform and Windowed filtering processing are carried out to it, obtaining optical path difference is d1Interference signal spatial spectrum, using inverse Fu It is d that vertical leaf transformation, which obtains optical path difference,1Reference interference signal 1 ', comparison refer to interference signal 1,2,3,4 and interference signal 1 ', can To be d to optical path difference1Interference signal identified.Detailed process is as follows:
Consider that reflectivity at distance z is the interference fringe of R, the interference spectrum signal of unilateral axial detection can table Up to formula are as follows:
Wherein, S (k) represents the spectral density function of swept light source, and k (t) represents the wave number changed over time, ordinary circumstance It is not the linear function of time down.Z representative sample depth coordinate and when z=0, correspond to the optical path difference of reference arm sample arm It is 0.δ z (t) represents the secondary resolution change in optical path length at depth z.
The analysis of cascade Mach-Zehnder interferometer interference spectrum signal can be based on the collision matrix of single-mode optical-fibre coupler, S2 For the collision matrix of 2 × 2 fiber couplers in cascade Mach-Zehnder interferometer, if the splitting ratio of 2 × 2 broadband optical fiber couplers is 1:1, then S2It can respectively indicate are as follows:
For a simple delay line system, transmission matrix, which is represented by, (has ignored common phase factor exp (-ikl1)):
Assuming that being from the input light field that fiber coupler 4 enters cascade Mach-Zehnder interferometerThe input light field exists The light symbol exported after interfering twice by 2 × 2 fiber couplers 18 in interferometerWithIt indicates, by S2With HdelayWrite out output light fieldWithExpression formula are as follows:
Wherein:
θ1=k ((l4-l3)-(l2-l1))
θ2=k (l2-l1)
θ3=k (l4-l3)
θ4=k ((l4-l3)+(l2-l1))
θ1、θ2、θ3And θ4Represent the transmission phase difference of Mach-Zehnder interferometer.Had ignored in formula (4) common item exp (- ikl1)、exp(-ikl2)、exp(-ikl3) and exp (- ikl4)。
15 second output terminal output light field of coupler isThe light intensity signal that then detector 16 detects may be expressed as:
The light intensity signal that balanced detector 10 detects may be expressed as:
Again because of (l2-l1)-(l4-l3)=d1, l2-l1=d2, l4-l3=d3, (l2-l1)+(l4-l3)=d4, then
P16∝(coskd2)S(k) (6)
P10∝(coskd2+coskd3+coskd4-coskd1)S(k) (7)
From formula (7) it can be seen that the interference spectrum signal that spectrum phase calibration interferometer detects includes that optical path difference is respectively d1,d2,d3,d4Cross-correlation item selects suitable l1、l2、l3And l4, so that optical path difference d2≈d3, d1< d2, then d1≈0；It is found that Interference signal 1,4 and 2 and 3 can be separated by the way that reasonable filter is arranged in balanced detector 10, but between 2,3 by Close in optical path difference, filter can not separate it；Detector 16 is added in cascade interferometer light path to optical path difference d2Letter Number identified, distinguishes interference signal 2 and interference signal 3.By optical path difference ascending interferometer point in present embodiment It Wei not optical path difference d1, optical path difference d2, optical path difference d3, optical path difference d4, optical path difference d5Main interferometer, calculate optical path difference d5It is final mesh 's.
Obtain distance d5Phase information specific step is as follows:
Light source 2 by optical path difference be D, phase change:
The π D ν/c of Δ φ=2 (8)
In formula, ν is light frequency, and c is the light velocity in vacuum.
Simultaneously:
The π of Δ φ=2 (N+ μ) (9)
In formula, N represents integer, and μ represents decimal.
Known to:
N+ μ=D ν/c (10)
It is d that laser frequency information when being sampled using the smallest interferometer of optical path difference and the h times, which is optical path difference here,1 Interferometer, determine its integral multiple phase:
In formula:In 1 indicate interferometer 1, h indicate sampling number.
For second swept light source 2 during frequency sweep, light source frequency detection unit 13 obtains 2 or 2 or more different frequencies Rate point marks m1、m2、...mn, corresponding frequency is respectively νm1、νm2、...νmn；By being fitted optical path difference d1Interferometer phase with The curve of 2 frequency of light source determines optical path difference d1The integral multiple phase of interferometer:
Definition: pmn=2n (νmn)νmn/ c, then (12) formula is changed to:
It is fitted using least square methodAnd pmnCurve determines L1With
It is rightIt is rounded:
It follows that optical path difference d1It is smaller, integral multiple phaseIt is more accurate.
When measuring simultaneously using the first swept light source 1 and the second swept light source 2, the first swept light source 1 is defined in optical path difference d1Interferometer in integral multiple phase beOn horizontal line represent the first swept light source 1.
Defined parameters SiAnd Δi:
Δ1Value and Δ2The method that laser beat frequency can be used in value obtains, the specific steps are as follows: the first swept light source 1 and the Two swept light sources 2 enter interferometer through fiber coupler 4, use the second output of 16 reception optical fiber coupler 15 of photodetector Spectrum interference signal is held, when the frequency of the first swept light source 1 and the second swept light source 2 is equal,Bring formula into (10): have:
ΔiTrue value be integer.To ΔiIt is rounded:
It obtainsWithAfterwards, it can determine
First swept light source 1, the second swept light source 2 are respectively to optical path difference d1And d2Interferometer use formula (10):
It can be derived by (21):
By S1、S2、Δ1And Δ2Bring formula (22) into:
(23) are write into as matrix form
In formula (24), k indicates total sampling number；Equation (24) are solved using least square method, obtain the whole of p grades of interferometers Several times phase SpAnd Δp。
By p estimated value SpAnd ΔpIt is rounded to immediate integer, to calculate the estimative figure for having discretization error:
Then estimated value is usedWithAs the integer phase of next iteration, above-mentioned calculating process process, until obtaining Obtain the integral multiple phase of all interferometersAnd small several times phase
Determine integral multiple phaseAnd small several times phaseAfterwards, under the ω times sampling situations, laser frequency vω, Distance valueAre as follows:
It is not difficult to find that the present invention can carry out dynamic measurement to absolute distance, ranging range is big, and precision reaches displacement interferometer survey The precision of amount.The present invention provides the iterative calculation methods of integral multiple phase and small several times phase, and distance is made to have higher standard True property, reliability.The present invention provides the measurement method of reference frequency, make distance that there is more stable length reference value, make away from From with higher repeatability, accuracy.

Claims (4)

1. a kind of double swept light source range-measurement systems based on cascade interferometer, including the first swept light source and the second swept light source, It is characterized in that, the light that first swept light source issues enters the first input end of the first photo-coupler, second frequency sweep The light that light source issues enters the first input end of the second photo-coupler, the first output end and the first light of second photo-coupler Second input terminal of coupler is connected, the first output end of first photo-coupler and the input of cascade Mach-Zehnder interferometer End is connected, and the output end of the cascade Mach-Zehnder interferometer is connected with the input terminal of balanced detector, and the cascading Mach was once Deccan interferometer is used to form spectral signal all the way, and providing optical path difference is d1The first reference signal, optical path difference d2Second ginseng Examine signal, optical path difference d3Third reference signal and optical path difference be d4The 4th reference signal；The of first photo-coupler Two output ends enter main interferometer, and the sample arm and reference arm of the main interferometer are total to road, including optical fiber circulator and collimator, The first end of the optical fiber circulator is connected with the second output terminal of the first photo-coupler, the light of second end through the collimator, Reflecting mirror reflecting part inside the collimator is divided back the optical fiber circulator, and the transmitted light of the collimator is incident upon tested On sample, the light splitting of reflecting part in collimator and it is mapped to the reflected light after sample and converges to form interference, the interference light of formation Third end through fiber optical circulator and the input terminal for entering third fiber coupler, two output ends of third fiber coupler with Two input terminals of the balanced detector are connected, the signal of the balanced detector detection through data collecting card and computer into The acquisition of row data and data processing；The second output terminal of second photo-coupler is detected with the light source frequency based on pid algorithm The input terminal of unit is connected；The light source frequency detection unit is incited somebody to action for identifying the Frequency point of the second swept light source As a result it exports to data collecting card and computer and carries out data acquisition and data processing.
2. double swept light source range-measurement systems according to claim 1 based on cascade interferometer, which is characterized in that the grade Join Mach-Zehnder interferometer include the one 2 × 2nd broadband optical fiber coupler, it is the 22 × 2nd broadband optical fiber coupler, the 32 × 2nd wide The light of band fiber coupler and the 42 × 2nd broadband optical fiber coupler, the first output end output of first photo-coupler passes through It is respectively l by length after one 2 × 2nd broadband optical fiber coupler light splitting1And l2Fiber arm enter the 22 × 2nd broadband Two input terminals of fiber coupler, light are wide into the 32 × 2nd by the first output end of the 22 × 2nd broadband optical fiber coupler Input terminal with fiber coupler, respectively by for l after second is divided3And l4Fiber arm enter the 42 × 2nd broadband The two-way output end of the input terminal of fiber coupler, the 42 × 2nd broadband optical fiber coupler is defeated with the balanced detector respectively Enter end to be connected；The second output terminal of 22 × 2nd broadband optical fiber coupler is connected with photodetector.
3. double swept light source range-measurement systems according to claim 1 based on cascade interferometer, which is characterized in that the light Source frequency detection unit includes collimator, beam expanding lens, spectroscope, the first detector, F-P cavity and the second detector, and described second The light of the second output terminal of photo-coupler enters the collimator, collimated to be expanded into the beam expanding lens, after expanding Light a part through the spectroscope reflection after enter first detector, another part through it is described it is spectroscopical transmission it is laggard The second detector is entered back into after entering F-P cavity；The signal of first detector and the second detector is directly entered the data and adopts Truck and computer carry out data acquisition and data processing.
4. the measurement side of double swept light source range-measurement systems according to claim 1 to 3 based on cascade interferometer Method, which comprises the following steps:
It (1) is d by the optical path difference of cascade Mach-Zehnder interferometer using balanced detector1The first reference signal, optical path difference d2 The second reference signal, optical path difference d3Third reference signal and optical path difference be d4The 4th reference signal separated；
(2) multiple and different Frequency points is obtained by light source frequency detection unit, by being fitted the smallest reference signal of optical path difference The phase of corresponding interferometer determines that the smallest reference signal of optical path difference is corresponding dry with the frequency curve of the second swept light source The integral multiple phase of interferometer and small several times phase；
(3) it is measured simultaneously using the first swept light source and the second swept light source, it is corresponding based on the smallest reference signal of optical path difference The integral multiple phase of interferometer and small several times phase obtained by way of iteration obtain all interferometers integral multiple phase and Small several times phase；
(4) in the ω times sampling according toCalculate dynamic absolute distance value, wherein vωIt is adopted for the ω times The frequency of second swept light source when sample, c are the light velocity,For the integral multiple phase of all interferometers,For all interferometers Small several times phase.
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CN110646805A (en) * 2019-09-04 2020-01-03 宁波核芯光电科技有限公司 Frequency modulation continuous wave laser ranging system based on virtual sweep frequency light source
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CN110646805B (en) * 2019-09-04 2023-01-24 宁波核芯光电科技有限公司 Frequency modulation continuous wave laser ranging system based on virtual sweep frequency light source
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CN110793444B (en) * 2019-10-24 2021-05-18 中国工程物理研究院流体物理研究所 Two-stage all-fiber frequency domain interference ranging method and device
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CN113567995A (en) * 2021-09-28 2021-10-29 武汉普赛斯电子技术有限公司 Laser ranging method and device
CN115327515A (en) * 2022-08-10 2022-11-11 哈尔滨工业大学 Double-sweep frequency interference dynamic measurement system and method based on phase transmission

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