CN203642944U - High-speed demodulation system of optical fiber F-P chamber sensor - Google Patents
High-speed demodulation system of optical fiber F-P chamber sensor Download PDFInfo
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- CN203642944U CN203642944U CN201420011678.5U CN201420011678U CN203642944U CN 203642944 U CN203642944 U CN 203642944U CN 201420011678 U CN201420011678 U CN 201420011678U CN 203642944 U CN203642944 U CN 203642944U
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Abstract
The utility model discloses a high-speed demodulation system of an optical fiber F-P chamber sensor. The system comprises a broadband light source, a three-port optical fiber circulator, a dense wavelength division multiplexing device, a photoelectric detector and an acquisition processing unit. Light emitted by the broadband light source is injected into the F-P chamber sensor through the three-port optical fiber circulator. Reflected light of the optical fiber F-P chamber sensor is injected into the dense wavelength division multiplexing device through the optical fiber circulator. The injected broadband reflected light after being filtered by the dense wavelength division multiplexing device is decomposed into three narrowband light with different wavelengths. The three narrowband light waves are injected into the photoelectric detector, then photoelectric conversion and filtering amplification are performed on the three narrowband light waves and then the acquisition processing unit carries out high speed sampling and data processing. A phase position or chamber length variation amount of the F-P chamber sensor to be measured is obtained through calculating. By using the system of the utility model, technology difficulty is reduced and system cost is greatly reduced too; and high speed and high precision modulation of the optical fiber F-P chamber sensor can be realized. The system is especially suitable for dynamic measurement, such as measurement of explosive wave pressure and the like.
Description
Technical field
The utility model belongs to technical field of optical fiber sensing, particularly relates to a kind of high speed (FBG) demodulator of fiber F-P cavity sensor.
Background technology
In optical fiber sensing system, the acting as of (FBG) demodulator: (1) continuously sends light signal to Fibre Optical Sensor; (2) receive the carrier signal that carries information to be measured, that is to say the signal that Fibre Optical Sensor returns, extract in the information we being needed through opto-electronic conversion, signals collecting, signal condition.(FBG) demodulator plays conclusive effect as the core component of whole optical fiber sensing system to the performance parameter such as precision, resolution of whole optical fiber sensing system.
In numerous Fibre Optical Sensors, the advantages such as fiber F-P cavity sensor is simple in structure with it, volume is little, high sensitivity, Fast Time Response, the transmission of single fiber signal receive the general concern of people, and becoming one of focus of optical fiber sensing technology in recent years and applied research thereof, this wherein also comprises the development of fiber F-P cavity sensor (FBG) demodulator matching used with it.Tool representative be Davidson company and the Canadian Opsens company of Canadian FISO company, the U.S., the fiber F-P cavity sensor (FBG) demodulator that they release, realize the measurement to parameters such as temperature, pressure and strains, and in civil engineering work, be applied.What the (FBG) demodulator of Qian Liang company adopted is non-scanning type correlation demodulation technology, and Opsens (FBG) demodulator adopts white light polarization interference technology, and these two kinds of technology all need wedge perfect in workmanship and line array CCD, and due to technical monopoly, (FBG) demodulator market price is high; The domestic research institution taking University Of Chongqing as representative has also carried out the systematic research of non-scanning type correlation demodulation, develop corresponding demodulating system, but the designing and making technology of wedge is also immature, cannot meet the required precision and stability requirement of demodulation, the practical very large gap in addition of distance.
The fiber F-P cavity sensor demodulating system of applying in Practical Project at present receives based on spectrometer mostly, and spectrometer is expensive, bulky, and can not realize the measurement of dynamic parameter, as measured explosion pressure etc.Therefore the fiber F-P cavity sensor (FBG) demodulator tool of, developing a kind of low cost, high precision, high frequency sound is of great significance.
Utility model content
The purpose of this utility model is to provide a kind of high-speed demodulating system of fiber F-P cavity sensor, and this demodulating system has advantages of that measuring accuracy is high, frequency response is high, cost is low.
The purpose of this utility model can adopt following technical scheme to realize: the high-speed demodulating system of described fiber F-P cavity sensor, comprise wideband light source, three fiber port circulators, dense wave division multiplexer, photodetector and acquisition process unit, between described wideband light source, three fiber port circulators, dense wave division multiplexer and photodetector, connect by optical fiber, between described photodetector and acquisition process unit, be connected by concentric cable; The light that wideband light source sends is by three fiber port circulator injection fibre F-P cavity sensors; The reflected light of fiber F-P cavity sensor injects dense wave division multiplexer via this optical fiber circulator again; The broadband reflection light of injection is decomposed into the narrow band light of three beams different wave length after dense wave division multiplexer filtering; This three beams arrowband light wave injects photodetector, after opto-electronic conversion and filter and amplification, carries out high-speed sampling and data processing by acquisition process unit, calculates phase place or the change of cavity length amount of F-P cavity sensor to be measured.
Described wideband light source is light emitting diode or fiber amplifier spontaneous radiation light source, and its output spectrum scope at least comprises 1540nm, 1550nm and tri-wavelength of 1560nm.
Three described fiber port circulator centre wavelengths are 1550nm;
Described dense wave division multiplexer comprises 1 input port, three output ports, and the centre wavelength of three output ports lays respectively near 1540nm, 1550nm, 1560nm, the about 0.2nm of spectrum width.
The photoelectric tube that described photodetector comprises three PIN types and supporting Low noise filter amplifying circuit thereof, the band of whole detector is wider than 500kHz;
Described photodetector San road output voltage should meet the principle that amplitude equates, zero-bit is consistent.
Described acquisition process unit comprises a high-speed a/d capture card and a computing machine, and A/D capture card is connected with computing machine by data communication port.
Compared with prior art, the utility model has technically compared with quantum jump: demodulation method described in the utility model is a kind of three-wavelength demodulation method based on random phase difference, traditional three-wavelength method adopts three independently LASER Light Source, and be equipped with and these three narrow-band optical filters that wavelength just in time mates, not only cost is higher, and is difficult to obtain matched filter; The utility model adopts wideband light source, and without the coupling of optical filter, in optical communication field, technology maturation, cheap dense wave division multiplexer can meet the filtering requirements of three-wavelength, greatly reduce system cost and technical difficulty.Simultaneously, because three-wavelength method is a kind of intensity demodulation method of offset-type, make fiber F-P cavity sensor high-speed demodulating system of the present utility model there is resolution high, measuring speed is fast, the many-sided advantage such as impact that is not subject to light source fluctuation is applicable to the high speed demodulation of fiber F-P cavity sensor very much.
Brief description of the drawings
Fig. 1 is system architecture schematic diagram of the present utility model.
In Fig. 11, wideband light source, 2, three fiber port circulators, 3, dense wave division multiplexer, 4, photodetector, 5, acquisition process unit, 6, fiber F-P cavity sensor.
Embodiment
By reference to the accompanying drawings, specific embodiment of the utility model is described.
As shown in Figure 1: demodulating system of the present utility model is mainly by wideband light source 1, three fiber port circulator 2, dense wave division multiplexer 3, photodetector 4 and acquisition process unit 5 form.Between described wideband light source 1, three fiber port circulators 2, dense wave division multiplexer 3 and photodetector 4, connect by optical fiber, between described photodetector 4 and acquisition process unit 5, be connected by concentric cable; The output light of wideband light source 1 injects the first port 21 of three fiber port circulators 2, again through circulator the second port 22 injection fibre F-P cavity sensors 6, the reflected light of fiber F-P cavity sensor re-injects the second port 22 of circulator, after the 3rd port 23 outputs via circulator, inject the input port 31 of dense wave division multiplexer 3, the broadband reflection light of injection is decomposed into the narrow band light of three beams different wave length after dense wave division multiplexer 3 filtering; This three beams arrowband light wave is exported by three output ports 32,33,34 of dense wave division multiplexer 3 simultaneously and is injected photodetector 4, after opto-electronic conversion and filter and amplification, carry out high-speed sampling and data processing by acquisition process unit 5, demodulation obtains the change of cavity length amount of F-P cavity sensor to be measured.Described wideband light source 1 is light emitting diode or fiber amplifier spontaneous radiation light source, and its output spectrum scope at least comprises 1540nm, 1550nm and tri-wavelength of 1560nm.Three described fiber port circulator 2 centre wavelengths are 1550nm; Described dense wave division multiplexer 3 comprises 1 input port, three output ports, and the centre wavelength of three output ports lays respectively near 1540nm, 1550nm, 1560nm, the about 0.2nm of spectrum width.The photoelectric tube that described photodetector 4 comprises three PIN types and supporting Low noise filter amplifying circuit thereof, the band of whole detector is wider than 500kHz; Described photodetector 4 San road output voltages should meet the principle that amplitude equates, zero-bit is consistent.Described acquisition process unit 5 comprises a high-speed a/d capture card and a computing machine, and A/D capture card is connected with computing machine by data communication port.
Demodulation principle of the present utility model is as follows:
For the fiber F-P cavity sensor of antiradar reflectivity (being that end face reflection rate is less than 10%), the catoptrical intensity of sensor
can be similar to by the cosine function of following formula and represent:
（1）
In formula,
for input light intensity,
for F-P chamber average reflectance,
for interfering visibility in F-P chamber,
for the phase place in F-P chamber,
Wherein,
for the length in F-P chamber,
for the refractive index of medium in F-P chamber,
for incident light wavelength.
In the above embodiments, the broadband reflection light of fiber F-P cavity sensor resolves into the arrowband light wave of three beams different wave length after via 1 × 3 dense wave division multiplexer 3 filtering, supposes that this three beams optical wavelength is respectively
,
,
, Ze Zhe tri-tunnel output light intensities can be expressed as
In formula,
,
,
with
,
,
corresponding wavelength respectively
,
,
incident intensity and output phase.
The electric signal of this three-beam after photodetector 4 opto-electronic conversion is
Jiang San road sine voltage signal
,
with
carry out data acquisition and analyzing and processing through acquisition process unit 5.According to three-wavelength demodulation principle, (FBG) demodulator three road light signals are through opto-electronic conversion with after amplifying, and the voltage of its output should meet the principle that sinusoidal signal amplitude equates, zero-bit is consistent as far as possible.Due to the unevenness of wideband light source Output optical power spectrum, the reason such as difference, the deviation of amplifying circuit resistance value of photoelectric tube responsiveness, the demodulator circuit that actual fabrication completes is difficult to meet the requirement of above-mentioned three-way output signal amplitude and zero-bit.This project adopts the method for carrying out digital normalization adjustment to gathering rear data to meet above-mentioned requirements, adopts software demodulation technology, and concrete grammar is as follows:
First, to each circuit-switched data collecting carry out Sine-Fitting obtain every road sinusoidal signal zero shift
and amplitude
, the zero shift of being then multiplied by the method Shi San road voltage signal of coefficient by Dui Mei road sinusoidal signal
and amplitude
unanimously, as follows by digital normalized Hou tri-road signals:
（5）
In formula
,
for the phase differential between this three beams light wave, can be obtained by foregoing Sine-Fitting.
Two formulas below of formula (5) are pressed to sine formula and launch, and order:
Can solve and draw:
Thus, tried to achieve the phase place in F-P chamber according to actual measurement San road voltage signal
, and
long with the chamber in sensor F-P chamber
between there is linear relationship as the formula (2), can try to achieve accordingly the change of cavity length in F-P chamber.Particularly, demodulating system of the present utility model is being used for to fiber F-P cavity sensor solution timing, first sensor is calibrated in laboratory, obtained the linear relationship between measured physical quantity and F-P cavity length or phase place by calibration, obtain the sensitivity coefficient of sensor; In the time that site test is tested, utilize demodulating system of the present utility model to measure phase place or the change of cavity length of sensor, realize the sensing of measured physical quantity according to the sensitivity coefficient of prior demarcation.
Although describe principle of the present utility model in detail with reference to above-described embodiment, should be appreciated that the utility model is not limited to the disclosed embodiments.For the technician of this professional domain, can carry out various changes to its form and details.The utility model is intended to contain the various modification in the spirit and scope of appended claims, as three fiber port circulators in the utility model can be with fiber coupler replacement etc.
Claims (7)
1. the high-speed demodulating system of a fiber F-P cavity sensor, it is characterized in that: described high-speed demodulating system comprises wideband light source, three fiber port circulators, dense wave division multiplexer, photodetector and acquisition process unit, between described wideband light source, three fiber port circulators, dense wave division multiplexer and photodetector, connect by optical fiber, between described photodetector and acquisition process unit, be connected by concentric cable; The light that wideband light source sends is by three fiber port circulator injection fibre F-P cavity sensors; The reflected light of fiber F-P cavity sensor injects dense wave division multiplexer via this optical fiber circulator again; The broadband reflection light of injection is decomposed into the narrow band light of three beams different wave length after dense wave division multiplexer filtering; This three beams arrowband light wave injects photodetector, after opto-electronic conversion and filter and amplification, carries out high-speed sampling and data processing by acquisition process unit, calculates phase place or the change of cavity length amount of F-P cavity sensor to be measured.
2. the high-speed demodulating system of a kind of fiber F-P cavity sensor according to claim 1, it is characterized in that: described wideband light source is light emitting diode or fiber amplifier spontaneous radiation light source, its output spectrum scope at least comprises 1540nm, 1550nm and tri-wavelength of 1560nm.
3. the high-speed demodulating system of a kind of fiber F-P cavity sensor according to claim 1, is characterized in that: three described fiber port circulator centre wavelengths are 1550nm.
4. the high-speed demodulating system of a kind of fiber F-P cavity sensor according to claim 1, it is characterized in that: described dense wave division multiplexer comprises 1 input port, three output ports, and the centre wavelength of three output ports lays respectively near 1540nm, 1550nm, 1560nm, the about 0.2nm of spectrum width.
5. the high-speed demodulating system of a kind of fiber F-P cavity sensor according to claim 1, is characterized in that: the photoelectric tube that described photodetector comprises three PIN types and supporting Low noise filter amplifying circuit thereof, the band of whole detector is wider than 500kHz.
6. a kind of high-speed demodulating system of fiber F-P cavity sensor according to claim 1 or 5, is characterized in that: described photodetector San road output voltage should meet the principle that amplitude equates, zero-bit is consistent.
7. the high-speed demodulating system of a kind of fiber F-P cavity sensor according to claim 1, is characterized in that: described acquisition process unit comprises a high-speed a/d capture card and a computing machine, and A/D capture card is connected with computing machine by data communication port.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103697922A (en) * | 2014-01-09 | 2014-04-02 | 中国人民解放军总参谋部工程兵科研三所 | High-speed demodulation system of optical fiber F-P cavity sensor |
| CN105973282A (en) * | 2016-05-20 | 2016-09-28 | 武汉理工大学 | Fiber F-P sensor cavity length wavelet phase extraction demodulation method |
| CN106017522A (en) * | 2016-05-11 | 2016-10-12 | 武汉理工大学 | Rapid high-precision signal demodulation method of fiber F-P sensor |
| CN108151866A (en) * | 2017-12-22 | 2018-06-12 | 电子科技大学 | A kind of Fabry-perot optical fiber sonic probe and signal demodulating system |
| CN108306686A (en) * | 2018-03-18 | 2018-07-20 | 肖世涛 | A kind of measuring device of high-accuracy light-adjustable filter wavelength tuning amount |
| CN108955734A (en) * | 2018-06-08 | 2018-12-07 | 武汉理工大学 | A kind of cavity length demodulating method of fiber F-P temperature/pressure compound sensor |
-
2014
- 2014-01-09 CN CN201420011678.5U patent/CN203642944U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103697922A (en) * | 2014-01-09 | 2014-04-02 | 中国人民解放军总参谋部工程兵科研三所 | High-speed demodulation system of optical fiber F-P cavity sensor |
| CN106017522A (en) * | 2016-05-11 | 2016-10-12 | 武汉理工大学 | Rapid high-precision signal demodulation method of fiber F-P sensor |
| CN105973282A (en) * | 2016-05-20 | 2016-09-28 | 武汉理工大学 | Fiber F-P sensor cavity length wavelet phase extraction demodulation method |
| CN105973282B (en) * | 2016-05-20 | 2018-10-09 | 武汉理工大学 | The long Wavelet Phase of fibre-optical F-P sensor chamber extracts demodulation method |
| CN108151866A (en) * | 2017-12-22 | 2018-06-12 | 电子科技大学 | A kind of Fabry-perot optical fiber sonic probe and signal demodulating system |
| CN108306686A (en) * | 2018-03-18 | 2018-07-20 | 肖世涛 | A kind of measuring device of high-accuracy light-adjustable filter wavelength tuning amount |
| CN108955734A (en) * | 2018-06-08 | 2018-12-07 | 武汉理工大学 | A kind of cavity length demodulating method of fiber F-P temperature/pressure compound sensor |
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