CN101799548B - All-fiber velocity measurement system and phase velocity measurement method - Google Patents

All-fiber velocity measurement system and phase velocity measurement method Download PDF

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CN101799548B
CN101799548B CN2010101128841A CN201010112884A CN101799548B CN 101799548 B CN101799548 B CN 101799548B CN 2010101128841 A CN2010101128841 A CN 2010101128841A CN 201010112884 A CN201010112884 A CN 201010112884A CN 101799548 B CN101799548 B CN 101799548B
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initial phase
optical fiber
light
circulator
measuring system
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CN101799548A (en
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吴重庆
王健
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Beijing Jiaotong University
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Abstract

The invention discloses an all-fiber velocity measurement system and a phase velocity measurement method. The system comprises a laser, a circulator and a self-focusing lens, wherein the end face of the self-focusing lens is a partially-transmitting end face; and the circulator is connected with an initial phase detection device and a parameter calculation device. The system also comprises an initial phase adjustment device. Laser light emitted by the laser is formed into reflected light and sensing light after passing through a first port and a second port of the circulator to reach the self-focusing lens, and after being output from a third port of the circulator, enters the initial phase detection device; an initial phase difference between the light intensity of the reflected light and the light intensity of the sensing light is detected; the initial phase adjustment device is utilized to adjust the initial phase difference so as to make the system work at a determined angle; and the parameter calculation device acquires the change of photocurrent intensity with time to obtain the change of phases with the time to further measure the kinematical parameters of velocity and acceleration. Through the system and the method, movements of moving objects with extremely short movement time and relatively higher velocity and acceleration can be accurately measured.

Description

Full optical fiber velocity-measuring system, phase place speed-measuring method
Technical field
The present invention relates to Fibre Optical Sensor and mechanical meaurement technical field, relate in particular to a kind of full optical fiber velocity-measuring system, phase place speed-measuring method.
Background technology
In the impact characteristics research of shock wave, blast physics and material, usually need measure the object of doing exercises.The motion of moving object has speed and acceleration is high, the characteristics of run duration weak point.In order to measure this motion, the interferometer (VISAR, VelocityInterferometer System for Any Reflector) that traditional method is to use the optics discrete component that any reflecting surface speed is measured.In recent years; Along with the development of optical fiber, optical passive component and relative photo electron device technology and perfect; Overcome not only based on the complete fine velocity-measuring system (FVISAR) of interfering of the light of optical fiber and optical fibre device that traditional velocity-measuring system is bulky, the shortcoming of debug difficulties, and had higher sensitivity and bigger dynamic range.
In present existing optical fiber velocity-measuring system, beat method (Velocimetry UsingHeterodyne Techniques) claims that also PDV method (Photonic Doppler Velocimetry) has good stability, is easy to measure the multiple spot velocity characteristic.
Basic PDV method is measured the number of reflecting surface speed based on the interference fringe that observes.Yet; Extremely lack (about hundreds of ns) for run duration; The not quite moving object of (the hundreds of m/s of velocity variations in tens ns) of speed but variation is exceedingly fast; The striped number that obtains only has several or tens, thus the number of cycles (fringe number) of the time-domain signal of interfering through observation be impossible measuring speed situation of change, more can not obtain the resolution that tests the speed of inferior ns magnitude.
Summary of the invention
The object of the present invention is to provide a kind of full optical fiber velocity-measuring system, speed-measuring method.Based on the present invention, it is extremely short to measure run duration accurately, and speed and acceleration be the motion of very high moving object all.
The invention provides a kind of optical fiber velocity-measuring system, comprise laser instrument, circulator, GRIN Lens and initial phase regulating device; Said circulator is connected with initial phase sniffer and parameter calculation apparatus; The end face of said GRIN Lens is a partial reflection part transmissive end face; The laser that said laser instrument sends is through forming reflected light and sense light behind first port, second port and the said GRIN Lens of said circulator; And after the 3rd port output of said circulator, get into said initial phase sniffer; Detect the first phase potential difference of said reflected light and said sense light light intensity; Utilize said initial phase regulating device to regulate the initial phase extent, make said system works in definite angle; Said parameter calculation apparatus obtains the photocurrent time-dependent variation in intensity obtaining phase place over time, and then measures the kinematic parameter that comprises speed and acceleration.
Above-mentioned optical fiber velocity-measuring system, said the 3rd port of preferred said circulator is connected with coupling mechanism, and said coupling mechanism comprises first output terminal and second output terminal, and said first output terminal is connected with the direct current detector to form said initial phase sniffer; Said second output terminal, interchange detector, oscillograph are connected with the composition parameter calculation element.
Above-mentioned optical fiber velocity-measuring system, preferred said coupling mechanism are 2 * 2 fiber coupler, and the minimum value, the maximal value that are detected the preceding difference frequency signal light intensity of moving object campaign by the direct current detector obtain just to differ.
Above-mentioned optical fiber velocity-measuring system, preferred said first output terminal is 10% output terminal, said second output terminal is 90% output terminal.
Above-mentioned optical fiber velocity-measuring system, preferred said phase differential regulating device is the manual fine-tuning frame, in order to light path between the probe of adjustment movement object and said GRIN Lens.
Above-mentioned optical fiber velocity-measuring system, preferred said phase differential regulating device is electronic micropositioning stage, in order to light path between the probe of adjustment movement object and said GRIN Lens.
Above-mentioned optical fiber velocity-measuring system, preferred said electronic micropositioning stage is driven by micromachine.
Above-mentioned optical fiber velocity-measuring system, preferred said electronic micropositioning stage is by Piezoelectric Ceramic.
The present invention also provides a kind of phase place speed-measuring method, carries out phase place based on above-mentioned arbitrary described full optical fiber velocity-measuring system and tests the speed, and may further comprise the steps: the first phase potential difference detects step, detects the first phase potential difference of said reflected light and said sense light light intensity; Regulating step utilizes the initial phase regulating device to regulate the initial phase extent, makes said system works in definite angle; The calculation of parameter step is obtained photocurrent by force over time obtaining phase place over time, and then is measured the kinematic parameter that comprises speed and acceleration.Than prior art, have following advantage in invention:
The first, through measure between sense light and the reference light phase differential over time, measure run duration and extremely lack (about hundreds of ns), greatly (the interior speed of tens ns accelerates to hundreds of m/s from zero to velocity variations, and acceleration reaches 10 7M/s 2More than) the speed of moving object, highly sensitive, the good stability that test the speed, measuring accuracy is high.
The second, only adopt a high speed detector and a common direct current detector to carry out phase measurement, cost is low, system's simple and stable.
Description of drawings
Fig. 1 is the structural representation of the full optical fiber velocity-measuring system of the present invention embodiment;
Fig. 2 is the structural representation of the full optical fiber velocity-measuring system of the present invention embodiment;
Fig. 3 is the flow chart of steps of phase place speed-measuring method embodiment of the present invention.
Embodiment
For make above-mentioned purpose of the present invention, feature and advantage can be more obviously understandable, below in conjunction with accompanying drawing and embodiment the present invention done further detailed explanation.
The present invention proposes a kind of phase measurement (hereinafter to be referred as surveying the phase method) of the optical fiber PDV system that is used for, and realizes the measurement of instantaneous velocity and acceleration.Survey the phase method and be through measure between sense light and the reference light phase differential over time, obtain the speed change with time.The method not only can be measured multiple speed, can also measure run duration and extremely lack (about hundreds of ns), and greatly (speed accelerates to hundreds of m/s from zero to velocity variations in tens ns, and acceleration reaches 10 7M/s 2More than) the speed of moving object.
With reference to Fig. 1, optical fiber velocity-measuring system of the present invention is by a laser instrument 1; 3, one first phase potential differences of 2, one GRIN Lens of circulator sniffer 9; A parameter calculation apparatus 11 (exchanging detector, an oscillograph) and 10 formations of a first phase potential difference regulating device.First phase potential difference sniffer 9 is made up of a coupling mechanism 5 and direct current photo-detector 6, is used for detecting the first phase potential difference of reference light and sense light.First phase potential difference regulating device 10 is manual or electronic micropositioning stage, and perhaps other produce the device of micrometric displacements, are used for the first phase potential difference is adjusted to a suitable angle.And then according to the light intensity that exchanges detection difference frequency signal on the detector 7 at a high speed over time, can obtain phase place over time.Because environment is very responsive to external world for the phase place of transmission light in the optical fiber, each initial phase difference of measuring is all inequality, and the key of therefore surveying the phase method is the measurement of initial phase difference.Because in the past monitoring system is all only used a high speed detector, and therefore high speed detector energy measurement direct current light not in fact can not obtain the first phase potential difference.
Fig. 2 is the structural representation of the full optical fiber velocity-measuring system of the present invention embodiment.Comprise laser instrument 1, circulator 2, GRIN Lens 3; Wherein, said circulator comprises first port 21, second port 22 and the 3rd port 23, and said GRIN Lens 3 comprises reflecting part and transmissive part; Said the 3rd port 23 places of said circulator 2 are connected with coupling mechanism 5, and said coupling mechanism 5 comprises 10% and 90% output terminal, and 10% output terminal is connected with direct current detector 6 to measure the first phase potential difference; 90% output terminal, interchange detector 7, oscillograph 8 are connected.
The laser that said laser instrument 1 sends is through first port 21 of said circulator 2, the end face that second port 22 arrives said GRIN Lens 3; Form emission light through said reflecting part; Be transmitted in the moving object 4 through said transmissive part; And the sense light that reflects to form of passing through said moving object 4; Said reflected light and said sense light output to said coupling mechanism 5 from the 3rd port 23 of said circulator 2, and the output terminal of said coupling mechanism 10% outputs to direct current detector 6 and carries out the calculating of first phase potential difference, and the light of said coupling mechanism 90% output terminal output gets into and exchanges detector 7 backs by oscillograph 8 records.Coupling mechanism 5 wherein is 2 * 2 fiber coupler.
If be initiated with 0 constantly with motion, the amplitude of reflected light and sense light is respectively E in the arrival interchange detector 7 10And E 20, the frequency of light carrier frequency is f, phase place is respectively
Figure GSA00000034596300051
With
Figure GSA00000034596300052
Then the two light field that arrives in the interchange detector 7 is respectively
Figure GSA00000034596300053
Figure GSA00000034596300054
Because the phase place of reference light (reflected light) does not receive the influence of moving object,
Figure GSA00000034596300055
Be a constant, so arrive the light intensity I that exchanges detector 7 Detector1For
Figure GSA00000034596300056
When moving object 4 during with high acceleration rapid movement; Phase place
Figure GSA00000034596300061
also changes fast; As long as the variation that has therefore recorded
Figure GSA00000034596300062
has also just recorded the motion conditions of moving object 4.The ultimate principle of survey phase method that Here it is.
It should be noted: exchanging detector 7 is that a high speed exchanges detector (lower-frequency limit is more than 10kHz usually), so the electric signal that gets into the oscillograph from detector 7 outputs has only the Alternating Component in (3) formula.
Be located at t=0 constantly; The instantaneous velocity of
Figure GSA00000034596300063
moving object is u (t), then
Figure GSA00000034596300064
arrive detector 7 difference frequency light phase place be remember
Figure GSA00000034596300066
so
Utilize manual or electronic method, regulate initial optical path difference, make
Figure GSA00000034596300068
So, detected alternating current i DetecFor
i det ec = 2 R I 1 I 2 sin [ 4 π λ ∫ 0 t u ( t ) dt ] - - - ( 5 )
Wherein R is the responsiveness of detector.Through parameters such as the speed that can draw moving object behind the differential, acceleration.
When, velocity ratio long when the time of moving object campaign was big, phase change was very big, was periodically, and periodicity (being also referred to as fringe number) is a lot.At this moment; Note
Figure GSA000000345963000610
is a fringe number, then
u ( t ) = λ 2 ∂ N ∂ t - - - ( 6 )
So can utilize (6) formula to measure the movement velocity of moving object again through measuring the changes delta N of the fringe number in the certain hour interval of delta t.
Very short when the run duration of moving object, when speed is not big especially yet, fringe number is seldom.If expect the process of velocity variations, can not measure the movement velocity of moving object through measuring the interior at interval fringe number of certain hour (this moment is less than a striped).Must just can calculate the movement velocity of moving object over time through measuring phase place in (5) formula.How explanation uses direct current detector 6 to measure first phase potential difference
Figure GSA00000034596300072
below
According to the proportionate relationship of coupling mechanism, the light intensity that arrives direct current detector 6 does
Figure GSA00000034596300073
Under the motionless situation of moving object, following formula becomes
Figure GSA00000034596300074
According to (8) formula, through the position of adjustment GRIN Lens, make the light intensity that arrives the direct current detector reach maximal value and minimum value respectively, at this moment (8) formula is written as respectively
I det ector 2 _ max = 1 9 ( I 1 + I 2 + 2 I 1 I 2 ) - - - ( 9 )
I det ector 2 _ min = 1 9 ( I 1 + I 2 - 2 I 1 I 2 ) - - - ( 10 )
Above two formulas of simultaneous obtain
I 1 + I 2 = 9 ( I det ector 2 _ max + I det ector 2 _ min ) 2 - - - ( 11 )
2 I 1 I 2 = 9 ( I det ector 2 _ max - I det ector 2 _ min ) 2 - - - ( 12 )
Can calculate I thus 1And I 2, and then the position of adjusting GRIN Lens, make the light intensity that arrives the direct current detector do
I det ector 2 _ π / 2 = 1 9 ( I 1 + I 2 ) - - - ( 13 )
Just can guarantee
Figure GSA00000034596300084
and utilize (6) formula to obtain the movement velocity of moving object at last.
On the other hand, the invention also discloses a kind of phase place speed-measuring method, comprise the steps: with reference to this method of Fig. 3
The first phase potential difference detects step 310, detects the first phase potential difference of said reflected light and said sense light light intensity; Regulating step 320 utilizes the initial phase regulating device to regulate the initial phase extent, makes said system works in definite angle; Calculation of parameter step 330 is obtained photocurrent by force over time obtaining phase place over time, and then is measured the kinematic parameter that comprises speed and acceleration.
The principle of said method embodiment and concrete ins and outs have been done clear complete explanation in system embodiment, repeat no more at this, each other mutually with reference to getting final product.
More than a kind of full optical fiber velocity-measuring system provided by the present invention, phase place speed-measuring method are introduced in detail; Used specific embodiment among this paper principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, part all can change on embodiment and range of application.In sum, this description should not be construed as limitation of the present invention.

Claims (9)

1. a full optical fiber velocity-measuring system is characterized in that, comprises laser instrument (1), circulator (2), GRIN Lens (3) and initial phase regulating device (10); Said circulator (2) is connected with initial phase sniffer (9) and parameter calculation apparatus (11); The end face of said GRIN Lens (3) is a partial reflection part transmissive end face;
The laser that said laser instrument (1) sends forms reflected light and sense light through first port (21), second port (22) and said GRIN Lens (3) back of said circulator (2); And after the 3rd port (23) output of said circulator, get into said initial phase sniffer (9); Detect the first phase potential difference of said reflected light and said sense light light intensity; Utilize said initial phase regulating device (10) to regulate the initial phase extent, make said system works in definite angle; Said parameter calculation apparatus (11) obtains the photocurrent time-dependent variation in intensity obtaining phase place over time, and then measures the kinematic parameter that comprises speed and acceleration.
2. full optical fiber velocity-measuring system according to claim 1; It is characterized in that; Said the 3rd port (23) of said circulator (2) locates to be connected with coupling mechanism (5); Said coupling mechanism (5) comprises first output terminal and second output terminal, and said first output terminal is connected with direct current detector (6) to form said initial phase sniffer (9); Said second output terminal, interchange detector (7), oscillograph (8) are connected with composition parameter calculation element (11).
3. full optical fiber velocity-measuring system according to claim 2 is characterized in that, said coupling mechanism (5) is 2 * 2 fiber coupler, and the minimum value, the maximal value that are detected the preceding difference frequency signal light intensity of moving object campaign by direct current detector (6) obtain just to differ.
4. full optical fiber velocity-measuring system according to claim 1 is characterized in that said first output terminal is 10% output terminal, and said second output terminal is 90% output terminal.
5. full optical fiber velocity-measuring system according to claim 1 is characterized in that said initial phase regulating device (10) is the manual fine-tuning frame, in order to light path between the probe of adjustment movement object and said GRIN Lens (3).
6. full optical fiber velocity-measuring system according to claim 1 is characterized in that said initial phase regulating device (10) is electronic micropositioning stage, in order to light path between the probe of adjustment movement object and said GRIN Lens (3).
7. full optical fiber velocity-measuring system according to claim 6 is characterized in that said electronic micropositioning stage is driven by micromachine.
8. full optical fiber velocity-measuring system according to claim 6 is characterized in that said electronic micropositioning stage is by Piezoelectric Ceramic.
9. a phase place speed-measuring method carries out phase place based on arbitrary described full optical fiber velocity-measuring system in the claim 1 to 8 and tests the speed, and it is characterized in that, may further comprise the steps:
The first phase potential difference detects step, detects the first phase potential difference of said reflected light and said sense light light intensity;
Regulating step utilizes the initial phase regulating device to regulate the initial phase extent, makes said system works in definite angle;
The calculation of parameter step is obtained the photocurrent time-dependent variation in intensity obtaining phase place over time, and then is measured the kinematic parameter that comprises speed and acceleration.
CN2010101128841A 2010-02-23 2010-02-23 All-fiber velocity measurement system and phase velocity measurement method Expired - Fee Related CN101799548B (en)

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CN112629640B (en) * 2019-10-08 2023-09-26 南京理工大学 Self-adaptive broadband vibration measuring system based on optical fiber Fizeau interference

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