CN102735181B - Laser self-mixing interference effect based fiber bragg grating signal demodulating system and method - Google Patents
Laser self-mixing interference effect based fiber bragg grating signal demodulating system and method Download PDFInfo
- Publication number
- CN102735181B CN102735181B CN201210244797.0A CN201210244797A CN102735181B CN 102735181 B CN102735181 B CN 102735181B CN 201210244797 A CN201210244797 A CN 201210244797A CN 102735181 B CN102735181 B CN 102735181B
- Authority
- CN
- China
- Prior art keywords
- laser
- fiber grating
- semiconductor laser
- signal
- wavelength
- 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
Abstract
The invention discloses a laser self-mixing interference effect based fiber bragg grating signal demodulating system and method, which can be used for the measurement of dynamic strain of fiber bragg gratings. Because a laser self-mixing interference measurement mode is adopted, compared with the prior art, the laser self-mixing interference effect based fiber bragg grating signal demodulating system and method provided by the invention not only have the advantage of high interference measurement method accuracy but also have the advantages of simple structure and small dimension because only a measurement channel is provided; a laser end voltage interference signal measurement method is adopted, the measurement bandwidth is not restricted by a photoelectric detector bandwidth any more, high-speed dynamic measurement can be realized, and moreover, as the photoelectric detector is reduced, the system cost is lowered, meanwhile, and the system reliability is also improved; and meanwhile, because of the unique characteristic of a laser self-mixing interference signal, the method also has the function of dynamic strain variation direction identification.
Description
Technical field
The present invention relates to the technical field of the measurement of strain, be specifically related to a kind of signal demodulating system and method for the fiber grating based on laser self-mixing interference effect, can be used for the measurement of fiber grating dynamic strain.
Background technology
Fiber-optic grating sensor only has an optical fiber, and sensitive element (grating) is produced in fibre core, the little and lightweight advantage from size, does not almost have other sensors can be by comparison; Simultaneously, as a kind of wavelength-modulated type optical sensor grown up on the basis of fiber grating, fiber-optic grating sensor not only inherits many advantages of ordinary optic fibre sensor: if not by electromagnetic interference (EMI), highly sensitive, fast response time, wide dynamic range, lightweight, compact conformation, use is flexible, cost is low, anticorrosive, high temperature resistant etc.; In addition, fiber-optic grating sensor also has some to be obviously better than the feature of ordinary optic fibre sensor: as Wavelength-encoding, be convenient to multiplexing, and be convenient to set up sensor network, be easy to introduce comprehensive treatment device signal is focused on etc.Just because of having advantages much more so, in recent years, the field such as the health monitoring of fiber-optic grating sensor in Aero-Space, boats and ships, battlefield monitoring, large scale civil engineering structure field and derived energy chemical is widely used.
The gordian technique of optical fiber grating sensing how accurately to demodulate the wavelength shift because measured change causes, therefore, development performance is good, price is low, practical demodulation techniques are breaches that current optical fiber grating sensor can obtain broader applications, traditional demodulation method mainly adopts monochromator-spectrometer and wavemeter to carry out demodulation, but the demodulated equipment of these schemes has the shortcomings such as volume is large-expensive, therefore the research of novel demodulation techniques obtains the very big concern of domestic and international research institution, and propose many new demodulation methods, be applicable to static demodulation method and comprise matched FBG filter method and Fabry one Perot (Fabry-Perot, F-P) tunable optic filter method, be applicable to dynamic demodulation method and comprise interferometric method, edge filter method, electric tunable semiconductor laser method, tunable optical amplify laser method, MEMS tunable optic filter method etc.At present, the fiber grating demodulation technology for low speed tempolabile signal is ripe, and for engineering.And more and more apply and propose demand to realizing high speed kinetic measurement, such as this kind of complication system of aviation aircraft, because modern Aviation aircraft is more and more higher to maneuverability requirement, corresponding power also from strength to strength, so the vibration of each system of aircraft is stronger, vibration frequency is higher, this makes in the system of this kind of complexity of aircraft, not only there are numerous static state or tempolabile signal (as temperature, pressure etc.), also there is a large amount of dynamic parametric tests, therefore seek highly sensitive, measure bandwidth, cost performance height and the simple high speed demodulation method of structure become problem demanding prompt solution.
Laser self-mixing interference measuring method provides a well selection for addressing this problem.So-called laser self-mixing interference, refer to that laser self-mixing interference refers to that the output light of laser instrument is reflected by exterior object or after scattering, wherein a part of light feeds back to laser resonant cavity again, feedback light carries exterior object information, after in resonator cavity, optical mode mixes mutually, the output power of modulated laser and frequency, form external optical feedback effect.Because output signal and traditional two-beam interference signal have similarity, therefore be called as laser self-mixing interference, be also referred to as laser feedback interference.As shown in Figure 1, in figure, M1 and M2 constitutes laser resonant cavity to its ultimate principle; M3 is the reflecting surface be positioned at outside resonator cavity, is called feedback mirrors, and it forms feedback exocoel together with M2; D is photodetector.The lengthwise movement of catoptron or cause the change of external cavity optical path length by the change of medium specific refractivity in chamber, by monitoring and for light sensing aspect, such as displacement, velocity survey, range finding etc.
Compared with having the conventional laser interferometer of " king of metering " good reputation, self-mixed interference method based on Laser feedback has identical phse sensitivity, and it has the feature of self uniqueness, first, self-mixed interference method only has one to interfere passage, structure is simple, compact, and traditional laser interferometer needs reference arm and gage beam two to interfere passage, complex structure; Secondly, self-mixed interference method does not rely on the coherent length of light source, can as the light source of self-mixed interference as common carbon dioxide laser and semiconductor laser yet, and traditional laser interferometer then requires as coherent source; Again, self-mixed interference method collimation is easily, simple to operate, low price, and traditional laser interferometer collimation difficulty, expensive.These advantages determine self-mixed interference method and have higher cost performance than traditional laser interferometer, are also simultaneously to realize wide range, preferred plan without guide rail, noncontact interferometry.Just because of the advantage of these uniquenesses, self-mixed interference measuring technique more and more obtains the concern of Chinese scholars, self-mixed interference measuring system is applied rapidly, instead of traditional, complicated interference system in a lot of application scenario and form a brand-new research field having far-reaching application prospect gradually.
To sum up, fiber grating sensing technology based on self-mixing interference effect combines that laser self-mixing interference technology acuracy is high, structure is simple, require the advantage such as low and the intrinsic advantage such as flexibility, susceptibility, reusability of fiber grating, is conducive to the sensor-based system realizing miniaturization.This development being fiber-optic grating sensor provides a kind of brand-new thinking.
Summary of the invention
The object of the invention is to propose a kind of fiber grating signal demodulating system based on laser self-mixing interference effect and method, the high speed that can realize dynamic strain is measured.
The technical solution used in the present invention is: a kind of fiber grating signal demodulating system based on laser self-mixing interference effect, this demodulating system is divided into light path part and circuit part, light path part realizes signal testing function, comprises semiconductor laser, single-mode fiber and fiber grating; Circuit part settling signal Acquire and process function, comprises the driving circuit of semiconductor laser, laser end tension measuring circuit, data collecting card and computing machine; Wherein, semiconductor laser is welded together with the single-mode fiber being carved with fiber grating, by semiconductor laser device driving circuit for semiconductor laser provides electric current driving and temperature to control, and obtain by laser end tension measuring circuit as the laser end voltage signal of measured signal, the measuring-signal obtained is sent into computing machine through data collecting card Real-time Collection and is processed, thus calculates the size of measured signal.Specifically as shown in Figure 2.
Wherein, described fiber grating is bragg grating.
Wherein, laser instrument is general commercial band tail optical fiber single mode semiconductor laser, as FP type semiconductor laser or DFB semiconductor laser.
Wherein, data collecting card selects general commercial single channel 16 bit data capture card, and sample frequency is greater than 500kHz.
The present invention provides a kind of fiber grating signal demodulating method based on laser self-mixing interference effect in addition, when fiber grating is subject to extraneous effect of stress, cause the reflection of fiber grating or the change of peak transmission wavelength, this causes the reflection kernel wavelength of fiber grating and the matching degree of semiconductor laser centre wavelength to change, this can cause the size of feedback light to change, and after feedback light mixes mutually with the optical mode in resonator cavity, form external optical feedback effect, also modulation is produced to laser end voltage, laser end voltage modulation signal is by after metering circuit process, gathered by data collecting card and be sent to computing machine, Labview or VC software programming computer program is utilized to extract fringe number and calculate tested strain, display response curve, concrete steps are see Fig. 5, specific as follows:
Step (1), by providing fixing drive current and control temperature in semiconductor laser device driving circuit, utilizing terminal voltage metering circuit unit to realize amplification process to terminal voltage signal, namely obtaining the measured information of modulating.
Step (2), by high-speed data acquisition card Real-time Collection terminal voltage signal, the data of collection are as the input of computing machine.
Step (3), in computing machine, utilize Labview or VC software programming computer program to extract striped number, and calculate tested strain size.
Step (4), in real time display result of calculation or curve.
Principle of the present invention is:
The present invention proposes a kind of high speed demodulation method of fiber-optic grating sensor signal, and its principle of work as shown in Figure 2.After the output light of semiconductor laser enters into the fiber grating with certain reflectivity, reflected light reenters laser resonant cavity as feedback, produce laser self-mixing interference effect, and the size of feedback light is relevant with the reflectivity size of fiber grating on the one hand, another aspect is relevant with the matching degree of semiconductor laser centre wavelength to the reflection kernel wavelength of fiber grating, when its reflection kernel wavelength mates with semiconductor laser centre wavelength, feedback light exports maximum.
When fiber grating is subject to effect of stress, the strain of generation finally can affect index modulation cycle and the fiber core refractive index of fiber grating, thus causes the reflection of fiber grating or the change of peak transmission wavelength.As shown in Figure 3, when fiber grating receives axial tension, center reflection wavelength increases λ 2 by λ 1, and the change of center reflection wavelength is linear with strain.When center reflection wavelength changes, this causes the reflection kernel wavelength of fiber grating and the matching degree of semiconductor laser centre wavelength to change, this can cause feedback light to change, thus the feedback striped of self-mixed interference is changed, therefore laser self-mixing effect is utilized, according to the change of feedback striped, the size of strain just can be demodulated.
The same with general interfere measurement technique, in self-mixed interference is measured, the bandwidth of measuring-signal is equally mainly limited to the bandwidth of photodetector.In self-mixed interference is measured, for simplifying system, the general photodetector adopting semiconductor laser built-in, because this detector is mainly as the change use of monitoring DC optical power, therefore its signal bandwidth is lower.When considering due to light field generation self-mixing interference effect in feedback light and laser cavity, not only to power, frequency modulation (PFM), and equally modulation is produced to the terminal voltage of laser instrument, therefore the present invention obtains interferometry signal by measuring laser end voltage, this makes bandwidth mainly be limited to treatment circuit, and treatment circuit can obtain very high bandwidth by appropriate design.
The advantage of the optical fibre grating high-speed demodulation method based on laser self-mixing interference effect of the present invention is:
(1), owing to adopting laser self-mixing interference metering system, therefore the present invention compared with the conventional method, not only has the advantage that interferometric method precision is high, simultaneously also because only have a Measurement channel to make system have structure is simple, size is little advantage;
(2), have employed the method for laser end voltage measurement interference signal in the present invention, make Measurement bandwidth no longer by the restriction of photodetector bandwidth, kinetic measurement at a high speed can be realized, and reduce system cost because decreasing photodetector, also improve the reliability of system simultaneously;
(3), due to laser self-mixing interference signal uniqueness, make the method have the function of dynamic strain change direction identification, this is the advantage that the present invention one is unique.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of laser mixed interference measuring principle.
Fig. 2 is the technical solution used in the present invention schematic diagram.
Fig. 3 is the principle schematic of demodulation method of the present invention.
Fig. 4 is demodulating system pie graph of the present invention.
Fig. 5 is the process flow diagram of demodulation method of the present invention.
Fig. 6 is the workflow diagram of computer software part of the present invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the present invention is further described.
Based on method of the present invention, the demodulating system of structure as shown in Figure 4.Mainly can be divided into light path part and circuit part.Light path part realizes signal testing function, mainly comprises semiconductor laser, single-mode fiber and fiber grating; Circuit part settling signal Acquire and process function, mainly comprises the driving circuit of semiconductor laser, laser end tension measuring circuit, data collecting card and computing machine etc.
The principle of work of system is when fiber grating is subject to extraneous effect of stress, cause the reflection of fiber grating or the change of peak transmission wavelength, this causes the reflection kernel wavelength of fiber grating and the matching degree of semiconductor laser centre wavelength to change, this can cause the size of feedback light to change, and after feedback light mixes mutually with the optical mode in resonator cavity, form external optical feedback effect, also modulation is produced to laser end voltage, modulation signal is by after metering circuit process, gathered by data collecting card and be sent to computing machine, utilize VC or Labview to prepare a computer program and extract and calculate tested strain, display response curve.For the demodulation of signal, adopt conventional Fringe-counting method, the method is simple, easily realizes.As for realizing high-precision measurement, Phase Demodulation Method of Optic can be adopted, as Active phase return zero technique, phase modulation technique etc.
Below in conjunction with accompanying drawing 4, concrete introduction is done to each several part in the present invention once.
Semiconductor laser is welded together with the single-mode fiber being carved with fiber grating, the light that semiconductor laser sends is sent to fiber grating through optical fiber, interference light after fiber grating reflection returns semiconductor laser through optical fiber, after this part feedback light mixes mutually with the optical mode in resonator cavity, form external optical feedback effect, when stress field acts on fiber grating, cause the change of the reflection wavelength of fiber grating, this causes the reflection kernel wavelength of fiber grating and the matching degree of semiconductor laser centre wavelength to change, this can cause feedback light to change, thus modulation is produced to laser end voltage, this modulation signal carries tested strain information, wherein semiconductor laser device driving circuit provides constant electric current to drive and temperature control for semiconductor laser, terminal voltage modulation signal is then after the process of laser end tension measuring circuit, this output signal is sent into computing machine through data collecting card Real-time Collection and is processed, utilize VC or Labview to prepare a computer program extract striped number and calculate tested strain size, display response curve.
(1) optical fiber and fiber grating
In the present invention, common single-mode fiber selected by optical fiber, and fiber lengths is decided according to the actual requirements.Fiber grating is bragg grating, and reflectivity can adjust according to actual design.
(2) semiconductor laser
In the present invention, laser instrument selects general commercial band tail optical fiber single mode semiconductor laser, can be FP type semiconductor laser or DFB semiconductor laser.
(3) drive circuit for laser
Semiconductor laser is as light source; need to use laser driver to provide constant Injection Current and working temperature for semiconductor laser; laser driver can use commercial driving instrument; also can self-developing circuit; but it should be noted that because semiconductor laser is rapid wear device, in order to protect semiconductor laser; in drive system, need that there is defencive function, need to add amplitude limiter circuit, slow start circuit, electrostatic discharge protective circuit.
(4) terminal voltage metering circuit
In the present invention, terminal voltage metering circuit realizes the measurement to interference signal, and instrument amplifier generally can be selected as the main devices of metering circuit.
(5) data collecting card
In the present invention, data collecting card realizes the high speed and real time sampling to current/voltage converter circuit output signal, selects general commercial single channel 16 bit data capture card (sample frequency is greater than 500kHz) to meet the demands.
(6) computing machine and data demodulates
In the present invention, computing machine is the demodulation of the core of whole system, main settling signal, calculates tested movable information, and display kinematic parameter curve, selects general pc machine to meet the demands.And sampling and processing software can adopt VC or Labview to develop realization, mainly comprise data acquisition module, data demodulation module, display module, treatment scheme is: first read measured data by data acquisition module from data collecting card, then data demodulation module is utilized to realize calculating and the calculating of strain size of number of interference fringes, show measured curve and size finally by display module, concrete treatment scheme as shown in Figure 6.
The technology contents that the present invention does not elaborate belongs to the known technology of those skilled in the art.
Although be described the illustrative embodiment of the present invention above; so that the technician of this technology neck understands the present invention; but should be clear; the invention is not restricted to the scope of embodiment; to those skilled in the art; as long as various change to limit and in the spirit and scope of the present invention determined, these changes are apparent, and all innovation and creation utilizing the present invention to conceive are all at the row of protection in appended claim.
Claims (1)
1. the fiber grating signal demodulating method based on laser self-mixing interference effect, this demodulation method is based on the fiber grating signal demodulating system of laser self-mixing interference effect, it is characterized in that: this demodulating system is divided into light path part and circuit part, light path part realizes signal testing function, comprises semiconductor laser, single-mode fiber and fiber grating; Circuit part settling signal Acquire and process function, comprises the driving circuit of semiconductor laser, laser end tension measuring circuit, data collecting card and computing machine; Wherein, semiconductor laser is welded together with the single-mode fiber being carved with fiber grating, by semiconductor laser device driving circuit for semiconductor laser provides electric current driving and temperature to control, and obtain by laser end tension measuring circuit as the laser end voltage signal of measured signal, the measuring-signal obtained is sent into computing machine through data collecting card Real-time Collection and is processed, thus calculates the size of measured signal;
Described fiber grating is bragg grating;
Laser instrument is general commercial band tail optical fiber single mode semiconductor laser, is specially FP type semiconductor laser or DFB semiconductor laser;
Data collecting card selects general commercial single channel 16 bit data capture card, and sample frequency is greater than 500kHz;
When fiber grating is subject to extraneous effect of stress, cause the reflection of fiber grating or the change of peak transmission wavelength, this causes the reflection kernel wavelength of fiber grating and the matching degree of semiconductor laser centre wavelength to change, this can cause feedback light to change, and after feedback light mixes mutually with the optical mode in resonator cavity, form external optical feedback effect, also modulation is produced to laser end voltage, laser end voltage modulation signal is by after metering circuit process, gathered by data collecting card and be sent to computing machine, Labview or VC software programming computer program is utilized to extract fringe number and calculate tested strain, display response curve, concrete steps are as follows:
Step (1), by providing fixing drive current and control temperature in semiconductor laser device driving circuit, utilizing terminal voltage metering circuit unit to realize amplification process to terminal voltage signal, namely obtaining the measured information of modulating;
Step (2), by high-speed data acquisition card Real-time Collection terminal voltage signal, the data of collection are as the input of computing machine;
Step (3), in computing machine, utilize Labview or VC software programming computer program to extract striped number, calculate tested strain size;
Step (4), in real time display result of calculation or curve;
Wherein, after the output light of semiconductor laser enters into the fiber grating with certain reflectivity, reflected light reenters laser resonant cavity as feedback, produce laser self-mixing interference effect, and the size of feedback light is relevant with the reflectivity size of fiber grating on the one hand, another aspect is relevant with the matching degree of semiconductor laser centre wavelength to the reflection kernel wavelength of fiber grating, and when its reflection kernel wavelength mates with semiconductor laser centre wavelength, feedback light exports maximum;
When fiber grating is subject to effect of stress, the strain produced finally can affect index modulation cycle and the fiber core refractive index of fiber grating, thus cause the reflection of fiber grating or the change of peak transmission wavelength, when fiber grating receives axial tension, center reflection wavelength increases λ 2 by λ 1, and the change of center reflection wavelength is linear with strain, when center reflection wavelength changes, this causes the reflection kernel wavelength of fiber grating and the matching degree of semiconductor laser centre wavelength to change, this can cause feedback light to change, thus the feedback striped of self-mixed interference is changed, therefore laser self-mixing effect is utilized, according to the change of feedback striped, just can demodulate the size of strain.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210244797.0A CN102735181B (en) | 2012-07-13 | 2012-07-13 | Laser self-mixing interference effect based fiber bragg grating signal demodulating system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210244797.0A CN102735181B (en) | 2012-07-13 | 2012-07-13 | Laser self-mixing interference effect based fiber bragg grating signal demodulating system and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102735181A CN102735181A (en) | 2012-10-17 |
| CN102735181B true CN102735181B (en) | 2015-06-10 |
Family
ID=46991118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210244797.0A Active CN102735181B (en) | 2012-07-13 | 2012-07-13 | Laser self-mixing interference effect based fiber bragg grating signal demodulating system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102735181B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106525097B (en) * | 2016-12-12 | 2019-08-13 | 大连艾科科技开发有限公司 | A kind of tunable laser wavelength detecting method and device |
| CN114111609A (en) * | 2021-11-19 | 2022-03-01 | 华能国际电力股份有限公司 | Gas turbine blade tip clearance monitoring system based on interference signal measurement method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4400680A1 (en) * | 1994-01-12 | 1995-07-13 | Kayser Threde Gmbh | Measurement of positional change using self-mixing interference laser |
| CN101013025A (en) * | 2007-02-09 | 2007-08-08 | 北京交通大学 | Optical fiber interference type on-line micro-displacement measuring system using fibre grating |
-
2012
- 2012-07-13 CN CN201210244797.0A patent/CN102735181B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4400680A1 (en) * | 1994-01-12 | 1995-07-13 | Kayser Threde Gmbh | Measurement of positional change using self-mixing interference laser |
| CN101013025A (en) * | 2007-02-09 | 2007-08-08 | 北京交通大学 | Optical fiber interference type on-line micro-displacement measuring system using fibre grating |
Non-Patent Citations (1)
| Title |
|---|
| Self-Mixing-Based Demodulation Technique for Dynamic Fiber Bragg Grating Strain Sensors;H.C.Seat et al;《IMTC2006-Instrumentation and Measurement Technology Conference》;20060427;2060-2065 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102735181A (en) | 2012-10-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101650509B (en) | Bragg grating high-speed demodulating system based on cascade-connection long period fiber grating | |
| CN101949685B (en) | Fiber laser self-mixing interferometer and measurement method thereof | |
| CN103364070B (en) | Fiber bragg grating vibration sensing system based on volume phase grating demodulation | |
| CN103697954B (en) | A kind of microcavity interference flow velocity pressure reduction sensitive structure and microcavity interference flow velocity of optical flow transducer | |
| CN102944253B (en) | Based on fiber grating transverse pressure and the temperature simultaneously measuring system of polarimetry | |
| CN102607621A (en) | Distributed optical fiber Brillouin sensing device and method thereof for detecting temperature and strain synchronously | |
| CN201477200U (en) | All-fiber type magnetic-field strength on-line sensing survey meter | |
| CN106802160B (en) | Fiber grating sensing demodulation system and method based on fork-shaped interference pattern | |
| CN104215368A (en) | F-P cavity optical fiber pressure sensing device and demodulation method thereof | |
| CN102589588A (en) | Method for demodulating cavity length of Fabry-Perot cavity by utilizing fiber Bragg gratings | |
| CN102778242A (en) | Demodulation method for Bragg grating | |
| CN103697923A (en) | Method for demodulating extrinsic fiber Fabry-Perot interferometer cavity length | |
| CN105093136A (en) | All-fiber weak magnetic field measuring device | |
| CN111579816B (en) | Acceleration measuring instrument based on photoelectric oscillator | |
| CN109186643A (en) | A kind of accurate sensor-based system and method for sensing based on reflection function resonance filter | |
| CN105092015A (en) | Non-contact fiber vibration sensing system and method | |
| CN110118532B (en) | Dual-wavelength nonlinear displacement demodulation method and system of fiber Fabry-Perot displacement sensor | |
| Mikhailov et al. | Multifunctional fiber-optic sensors for space infrastructure | |
| CN102735181B (en) | Laser self-mixing interference effect based fiber bragg grating signal demodulating system and method | |
| CN101738167A (en) | Resonant cavity frequency stabilization-based absolute distance measurement system and implementing method thereof | |
| Baptista et al. | Mach-Zehnder and Michelson topologies for self-referencing fibre optic intensity sensors | |
| CN201716502U (en) | Bragg grating high-speed demodulating system based on cascading long-period fiber bragg grating | |
| CN201130028Y (en) | Optical fibre grating sensor demodulation instrument | |
| CN1304900C (en) | Optical fibre grating wavelength demodulating method | |
| CN204101218U (en) | A kind of F-P cavity fiber pressure sensing device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |