CN204730935U - Based on the laser interference vibration detection device of ultrasound wave external modulation - Google Patents
Based on the laser interference vibration detection device of ultrasound wave external modulation Download PDFInfo
- Publication number
- CN204730935U CN204730935U CN201520481958.7U CN201520481958U CN204730935U CN 204730935 U CN204730935 U CN 204730935U CN 201520481958 U CN201520481958 U CN 201520481958U CN 204730935 U CN204730935 U CN 204730935U
- Authority
- CN
- China
- Prior art keywords
- fiber
- output terminal
- laser
- input end
- vibration detection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
The utility model discloses a kind of laser interference vibration detection device based on ultrasound wave external modulation, the output terminal of fiber laser is connected to the input end of 3db fiber optic splitter, first output terminal of described 3db fiber optic splitter is connected to the first input end of optical-fiber bundling device, second output terminal of 3db fiber optic splitter is connected to the first input face of measurement target, second input face of described measurement target is connected with PZT and ultrasonic generator, the output face of measurement target is connected with optical receiver antenna input end, described optical receiver antenna output terminal is connected with another input end of described optical-fiber bundling device, the output terminal of optical-fiber bundling device is connected with the input end of detector, the output terminal of described detector is connected with detuner input end, detuner carries out PGC+DCM demodulation to the signal that detector exports.The utility model makes heterodyne phase shifting frequencies change with ultrasonic frequency change, and realizing bandwidth B value reduces 4-5 the order of magnitude, and detection sensitivity can reach sub-nanometer scale, significantly improves the precision of vibration detection.
Description
Technical field
The utility model relates to a kind of vibration detection device, particularly relates to a kind of laser interference vibration detection device based on ultrasound wave external modulation.
Background technology
Heterodyne laser interferometer because of its high resolving power, advantages such as high precision and being widely used.But along with the raising of accuracy of detection, the accuracy of detection of heterodyne laser interferometer is the key factor affecting its measuring accuracy.Therefore, the accuracy of detection improving laser interferometer improves the important leverage of its measuring accuracy.In order to solve laser interference vibration survey problem, German polytic company, U.S.'s light utility companies has carried out laser doppler vibration measuring instrument development, and its measuring accuracy can only reach nm magnitude.In laser interference vibration survey, it is one of conventional method that acousto-optic frequency translation produces heterodyne, and in the Random speckle Modulation Technique for Laser Interferometry delivered according to Peter B etc.: the precision that difference interference detects is expressed as follows shown in formula:
)(4hvB/Pη)
1/2K
-1
Wherein λ is wavelength, and h is Planck's constant, and B is bandwidth, and P is received power, and η is photoelectric transformation efficiency, and v is laser frequency, and K is constant.
It can thus be appreciated that, when B more hour, observable object vibration value is less, and polytic company and U.S.'s light utility companies adopt traditional acousto-optic frequency translation method as heterodyne frequency shift, its B value is generally greater than 40MHz, therefore the space that much can improve in addition of its accuracy of detection.
For improving accuracy of detection, when other situation is constant, detection sensitivity can be improved by changing B.China Patent No. is 200910241696.6, the applying date is that a kind of " modulation demodulation system for vibration detection and the method " on Dec 2nd, 2009 discloses employing PZT (Piezoelectric Ceramic Transducer, piezoelectric ceramics) drive reflection to cause the method for change in optical path length, but in the method, PZT itself has non-linear, bring comparatively big error to vibration survey, minute surface will keep vertical grade all to there is difficulty all the time in moving process with incident light simultaneously.
Because measurement target is diffuse reflector, so its hot spot reflected is speckle, speckle means hot spot skewness, if when detector is just in speck position, system signal noise ratio is higher, and when measurement target is vibrated, speckle moves, what detector detected may be darker place, and now signal to noise ratio (S/N ratio) can become very poor.
Utility model content
The purpose of this utility model overflows the uneven technical matters of the speckle launched for solving low, the single PZT Modulation and Nonlinear of current heterodyne laser interference vibration-detecting instrument detection sensitivity and measurement target.
In order to solve the problems of the technologies described above, the utility model provides a kind of laser interference vibration detection device based on ultrasound wave external modulation, the output terminal of fiber laser is connected to the input end of 3db fiber optic splitter, first output terminal of described 3db fiber optic splitter is connected to the first input end of optical-fiber bundling device, second output terminal of 3db fiber optic splitter is connected to the first input face of measurement target, second input face of described measurement target is connected with PZT and ultrasonic generator, the output face of measurement target is connected with optical receiver antenna input end, described optical receiver antenna output terminal is connected with another input end of described optical-fiber bundling device, the output terminal of optical-fiber bundling device is connected with the input end of detector, the output terminal of described detector is connected with detuner input end.
Further, the ultrasonic signal frequency that described ultrasonic generator produces is 20KHz, and signal intensity is 100db.
Further, described PZT is close to described measurement target, and the vibration frequency of PZT is less than 2KHz, and amplitude is less than 1/4th of described fiber laser Output of laser wavelength.
Further, the vibration frequency of described PZT is 1KHz.
Further, described fiber laser is that narrow linewidth is protected partially and frequency stabilized laser.
Further, the live width of described fiber laser is less than 10KHz.
Further, the splitting ratio of described 3db fiber optic splitter is 50%.
Further, all optical fiber be connected with described 3db fiber optic splitter are polarization maintaining optical fibre.
Further, described measurement target is glass or aluminium sheet.
Further, the frequency bandwidth >1MHz of described detector.
The utility model can make heterodyne phase shifting frequencies change with ultrasonic frequency change.Because ultrasonic frequency can be adjusted lower relatively, so its bandwidth B value is smaller, can realize bandwidth B value and reduce 4-5 the order of magnitude, detection sensitivity can reach sub-nanometer scale, significantly improves the precision of vibration detection.Meanwhile, the nonlinear problem that ultrasound wave external modulation mode also can be avoided adopting PZT modulation and draw, improves the irreflexive speckle non-uniformity problem of measurement target.The utility model structure is more simply compact, reduces system cost, improves system stability.
Accompanying drawing explanation
Fig. 1 is based on ultrasound wave external modulation laser interference vibration detection structure schematic diagram;
Fig. 2 is PGC+DCM demodulation principle block diagram;
Fig. 3 is the vibration signal waveforms demodulated.
In figure: 1. fiber laser; 2.3db fiber optic splitter; 3. measurement target; 4.PZT; 5. ultrasonic generator; 6. optical receiver antenna; 7. optical-fiber bundling device; 8. detector; 9. detuner.
Embodiment
In conjunction with the accompanying drawings and embodiments the utility model is described in further detail now.These accompanying drawings are the schematic diagram of simplification, only basic structure of the present utility model are described in a schematic way, and therefore it only shows the formation relevant with the utility model, and it should not be construed as restriction of the present utility model.
As shown in Figure 1, the output terminal of fiber laser 1 is connected to the input end of 3db fiber optic splitter 2, and fiber laser 1 is for narrow linewidth guarantor is inclined and frequency stabilized laser, and live width is less than 10KHz, and wavelength is 1550nm, 3db fiber optic splitter 2 is polarization-maintaining beam splitter, its splitting ratio is 50%, the all optical fiber be connected with 3db fiber optic splitter 2 are polarization maintaining optical fibre, first output terminal of 3db fiber optic splitter 2 is connected to the first input end of optical-fiber bundling device 6, second output terminal of 3db fiber optic splitter 2 is connected to the first input face of measurement target 3, second input face of measurement target 3 is connected with PZT4 and ultrasonic generator 5, the output face of measurement target 3 is connected with the input end of optical receiver antenna 6, measurement target 3 is the reflecting medium such as glass or aluminium sheet, the input end of optical receiver antenna 6 receives diffusing and being coupled into optical fiber of measurement target 3, its output terminal connecting fiber bundling device 7, the output terminal of optical receiver antenna 6 is connected with another input end of optical-fiber bundling device 7, the output of optical-fiber bundling device 7 forms interference field, the output terminal of optical-fiber bundling device 7 is connected with the input end of detector 8, the frequency bandwidth >1MHz of detector 8, interference signal is detected by detector 8, the output terminal of detector 8 is connected with the input end of detuner 9, the signal that detuner 9 pairs of detectors 8 export carries out PGC+DCM demodulation,
The frequency that ultrasonic generator 5 produces is 20KHz, intensity is the vibration frequency that ultrasonic signal and the PZT4 that is close to measurement target 3 of 100db produces is 1KHz, the vibration signal that amplitude is less than fiber laser 1 Output of laser wavelength 1/4th drives measurement target 3 to vibrate simultaneously, the signal that optical receiver antenna 6 is received produces Doppler shift, the light that the signal that optical receiver antenna 6 exports enters after optical-fiber bundling device 7 and 3db fiber optic splitter 2 inputs to optical-fiber bundling device 7 interferes, generate interference signal, in this interference signal, wherein ultrasonic signal frequency is higher, be defined as carrier phase shift, and PZT signal is the microvibration signal needing to detect, then interference system produces optical path difference, form outer phase-modulation.
Measurement target 3 is connected with PZT4 and supersonic signal generator 5, thus obtain vibration signal, simultaneously, measurement target 3 receives the incident light from 3db fiber optic splitter 2, and is connected with optical receiver antenna 6 by irreflexive mode, forms Doppler signal by which, wherein ultrasound wave can be set to phase place shift frequency carrier wave, PZT4 signal is the Vibration Signal in Frequency Domain that need detect, after being detected by detector 8 by traditional PGC+DCM demodulation method by its demodulation out, as shown in Figure 2.
After fiber laser 1 is opened, narrow linewidth laser sends single mode narrow-linewidth laser, laser carries out light splitting by 3db fiber optic splitter 2, wherein a road enters in optical-fiber bundling device 7, an other road is irradiated to measurement target 3, measurement target 3 is vibrated under ultrasonic generator 5 and PZT4 drive, and ultrasonic generator 5 causes measurement target Oscillation Amplitude to be:
, PZT4 causes measurement target Oscillation Amplitude to be:
, then the light be irradiated in measurement target 3 is received by light receiver aerial 6, and is coupled in optical-fiber bundling device 7, in optical-fiber bundling device 7, and the interference of two-way light, the interference signal that detector 8 detects is:
,
Wherein,
,
.
For
Traditional PGC+DCM(Phase Generated Carrier+Differentiate Cross Multiply can be adopted, phase generated carrier+microwave multiplication cross) demodulation mode, concrete demodulation method and China Patent No. are that the demodulating algorithm in a kind of " modulation demodulation system for vibration detection and the method " of 200910072532.5 is identical, the impact of disturbance on system can be eliminated, improve signal to noise ratio (S/N ratio), can demodulate well simultaneously
.
When PZT driver for PZT4 provides amplitude to be 0.01v, cycle is when being 400Hz signal, the Oscillation Amplitude of PZT4 is pm magnitude, therefore the Oscillation Amplitude of measurement target 3 is also pm magnitude, when adopting acousto-optic frequency translation heterodyne to detect, because bandwidth B is too wide, accuracy of detection is examined not and is not measured signal, adopt the utility model to carry out detection process, can obtain the 400Hz signal that signal to noise ratio (S/N ratio) is good, the vibration signal waveforms that last solution recalls as shown in Figure 3.
With above-mentioned according to desirable embodiment of the present utility model for enlightenment, by above-mentioned description, relevant staff in the scope not departing from this utility model technological thought, can carry out various change and amendment completely.The technical scope of this utility model is not limited to the content on instructions, must determine its technical scope according to right.
Claims (10)
1. based on the laser interference vibration detection device of ultrasound wave external modulation, it is characterized in that, the output terminal of fiber laser is connected to the input end of 3db fiber optic splitter, first output terminal of described 3db fiber optic splitter is connected to the first input end of optical-fiber bundling device, second output terminal of 3db fiber optic splitter is connected to the first input face of measurement target, second input face of described measurement target is connected with PZT and ultrasonic generator, the output face of measurement target is connected with optical receiver antenna input end, described optical receiver antenna output terminal is connected with another input end of described optical-fiber bundling device, the output terminal of optical-fiber bundling device is connected with the input end of detector, the output terminal of described detector is connected with detuner input end.
2. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1, is characterized in that, the ultrasonic signal frequency that described ultrasonic generator produces is 20KHz, and signal intensity is 100db.
3. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1 and 2, it is characterized in that, described PZT is close to described measurement target, and the vibration frequency of PZT is less than 2KHz, and amplitude is less than 1/4th of described fiber laser Output of laser wavelength.
4. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1, is characterized in that, the vibration frequency of described PZT is 1KHz.
5. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1, is characterized in that, described fiber laser is that narrow linewidth is protected partially and frequency stabilized laser.
6. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 5, it is characterized in that, the live width of described fiber laser is less than 10KHz.
7. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1, is characterized in that, the splitting ratio of described 3db fiber optic splitter is 50%.
8. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 7, is characterized in that, all optical fiber be connected with described 3db fiber optic splitter are polarization maintaining optical fibre.
9. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1, is characterized in that, described measurement target is glass or aluminium sheet.
10. the laser interference vibration detection device based on ultrasound wave external modulation according to claim 1, is characterized in that, the frequency bandwidth >1MHz of described detector.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201520481958.7U CN204730935U (en) | 2015-07-06 | 2015-07-06 | Based on the laser interference vibration detection device of ultrasound wave external modulation |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201520481958.7U CN204730935U (en) | 2015-07-06 | 2015-07-06 | Based on the laser interference vibration detection device of ultrasound wave external modulation |
Publications (1)
Publication Number | Publication Date |
---|---|
CN204730935U true CN204730935U (en) | 2015-10-28 |
Family
ID=54389276
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN201520481958.7U Active CN204730935U (en) | 2015-07-06 | 2015-07-06 | Based on the laser interference vibration detection device of ultrasound wave external modulation |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN204730935U (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106441544A (en) * | 2016-10-14 | 2017-02-22 | 南京理工大学 | Portable optical measuring instrument |
CN109905177A (en) * | 2019-03-13 | 2019-06-18 | 华南师范大学 | Radio digital communication receiving antenna and its method based on the relevant conversion of microwave light wave |
-
2015
- 2015-07-06 CN CN201520481958.7U patent/CN204730935U/en active Active
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106441544A (en) * | 2016-10-14 | 2017-02-22 | 南京理工大学 | Portable optical measuring instrument |
CN106441544B (en) * | 2016-10-14 | 2019-01-18 | 南京理工大学 | A kind of portable optical measuring instrument |
CN109905177A (en) * | 2019-03-13 | 2019-06-18 | 华南师范大学 | Radio digital communication receiving antenna and its method based on the relevant conversion of microwave light wave |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN104931126A (en) | A laser interference vibration detection apparatus based on supersonic wave external modulation | |
Muanenda et al. | Dynamic phase extraction in a modulated double-pulse ϕ-OTDR sensor using a stable homodyne demodulation in direct detection | |
JP6698164B2 (en) | Optical frequency domain reflection method and system based on frequency synthesis | |
US8144334B2 (en) | Fiber-optic, digital system for laser Doppler vibrometers (LDVs) | |
CN103196584B (en) | Measurement method for temperature and stress in fiber and Brillouin optical time domain reflectometer | |
WO2021017098A1 (en) | Differential laser interferometric nanometer displacement measurement apparatus and method employing sinusoidal phase modulation | |
WO2015176362A1 (en) | Light pulse compression reflector apparatus | |
CN102384799B (en) | Frequency sweeping and data processing method based on Brillouin distributed fiber sensing system correlation detection scheme | |
Wu et al. | Distributed fiber voice sensor based on phase-sensitive optical time-domain reflectometry | |
WO2017067255A1 (en) | Processing method and device for use in coherent phase-sensitive optical time-domain reflectometer | |
CN110108346A (en) | Optical fibre vibration sensor based on delay phase modulation chirped pulse pair | |
Yang et al. | A PGC demodulation based on differential-cross-multiplying (DCM) and arctangent (ATAN) algorithm with low harmonic distortion and high stability | |
CN204730935U (en) | Based on the laser interference vibration detection device of ultrasound wave external modulation | |
Li et al. | Sagnac vibration sensing system with nested pulse method | |
Wosniok et al. | L-BOFDA: a new sensor technique for distributed Brillouin sensing | |
CN114754689A (en) | Phase type distance measuring device and method based on double-electro-optical heterodyne modulation | |
Zhang et al. | Dual-Sagnac optical fiber sensor used in acoustic emission source location | |
Song et al. | Brillouin optical correlation domain analysis in linear configuration | |
CN102636337A (en) | Method for measuring optical fiber dispersion | |
Mizuno et al. | Phase-detected Brillouin optical correlation-domain reflectometry | |
CN108007307B (en) | Optical fiber measuring method and measuring device | |
US20220128383A1 (en) | OTDR measurement via wavelength/frequency sweeping in phase-sensitive DAS/DVS systems | |
Wang et al. | Coherent OTDR with large dynamic range based on double-sideband linear frequency modulation pulse | |
CN115839762A (en) | Double-pulse long-distance distributed vibration detection device and detection method based on OFDR principle | |
CN203224310U (en) | Brillouin optical time domain reflectometer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
C14 | Grant of patent or utility model | ||
GR01 | Patent grant |