CN102818655A - Reflection-type temperature sensor based on optical fiber radiation induced attenuation temperature characteristics - Google Patents
Reflection-type temperature sensor based on optical fiber radiation induced attenuation temperature characteristics Download PDFInfo
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- CN102818655A CN102818655A CN2012102798464A CN201210279846A CN102818655A CN 102818655 A CN102818655 A CN 102818655A CN 2012102798464 A CN2012102798464 A CN 2012102798464A CN 201210279846 A CN201210279846 A CN 201210279846A CN 102818655 A CN102818655 A CN 102818655A
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Abstract
The invention provides a reflection-type temperature sensor based on optical fiber radiation induced attenuation temperature characteristics. Light emitted from a light source is divided into two beams of light with the same intensity through a coupler, wherein one beam of light reaches a photodiode through optical fiber, and the other beam of the light enters a temperature sensitive element through the optical fiber and is reflected by a reflection device to return at the tail end of the optical fiber; the light intensity is modulated by a temperature field, and the light reaches to another photodiode through the coupler and the optical fiber; photoelectrical signals are transformed by the two photodiodes and are transmitted to a signal processing and light source drive circuit; and a temperature value is determined by the signal processing and light source drive circuit according to the received two ways of photoelectrical signals. With the adoption of the reflection-type temperature sensor based on the optical fiber radiation induced attenuation temperature characteristics, all fiber temperature measurement is realized; and the reflection-type temperature sensor has the advantages of being high in safety, relatively low in cost and higher in measuring precision and resisting electromagnetic interference; and the used temperature sensitive element has the characteristic of being simple in manufacturing process and flexible in design.
Description
Technical field
The present invention relates to a kind of reflective temperature sensor, belonged to Fibre Optical Sensor and temperature measurement technology field based on optical fiber radiation induced attenuation temperature characterisitic.
Background technology
Temperature is one of important parameter of observing and controlling in the industrial processes, is the important operational factor of equipment.Many physical phenomenons of object are all relevant with temperature with chemical property, too high or too low for temperaturely all can impact product and equipment, even can make product rejection, device damage.Therefore, in national defence, military affairs, scientific experiment and industrial and agricultural production process, the measurement and the control of temperature have a very important role.
Under the support of semiconductor technology, developed in succession this century and comprised the semiconductor thermocouple sensor at interior various temperature sensor.Corresponding with it, according to the interaction rule of ripple and material, developed acoustics temperature sensor, infrared sensor and microwave remote sensor in succession.The kind of temperature sensor is a lot, and resistance temperature detector, thermocouple temperature sensor, bimetallic temperature sensor, quartz resonance type temperature sensor etc. are arranged.But in inflammable, explosive, narrow space, have corrosive atmosphere or have under the rugged surroundings of electromagnetic interference (EMI), traditional temperature measurement technology receives very big restriction, even can't work.The sensing head of fibre optic temperature sensor is not charged, and optical fiber has characteristics such as volume is little, in light weight, flexible, anti-electromagnetic interference (EMI), makes fibre optic temperature sensor have remarkable advantages in these applications.
Fibre optic temperature sensor mainly comprises Fiber Bragg Grating FBG (FBG) temperature sensor, semiconductor absorption fibre optic temperature sensor and optical fiber Fabry-POLO chamber interference type temperature sensor etc. at present.Wherein optical fiber Bragg grating temperature sensor adopts wavelength-modulated, and demodulating system is complicated, and the problem of temperature-stress cross-inductive is arranged.Semiconductor absorption fibre optic temperature sensor manufacturing process is complicated, and technological requirement is higher, need expensive ultraviolet wideband light source and optical fiber is had higher requirements, and coupling efficiency is lower than direct coupling, and measuring accuracy is lower, has only usually ± 1 ℃.And the complex manufacturing technology of optical fiber Fabry-POLO chamber interference type temperature sensor, consistance is difficult to guarantee that the complicated temperature sensor scope of demodulating system is very limited.
Summary of the invention
The present invention will provide a kind of reflective temperature sensor based on optical fiber radiation induced attenuation temperature characterisitic; The manufacturing process that the existing fiber temperature sensor exists is complicated, signal demodulating system is complicated in order to solve, cost is than problems such as height, improves the sensitivity of thermometric.
Reflective temperature sensor based on optical fiber radiation induced attenuation temperature characterisitic of the present invention comprises: light source, coupling mechanism, measurement light path, reference path, two photodiodes and signal Processing and light source driving circuit.
Signal Processing and light source driving circuit are that light source provides power supply; Light source connects coupling mechanism through optical fiber; Coupling mechanism connects temperature-sensing element (device), first photodiode and second photodiode respectively through optical fiber; Two photodiodes all send electrical signal converted to signal Processing and light source driving circuit through electric wire, and signal Processing and light source driving circuit are handled two path signal, convert temperature value to; Measuring light path comprises temperature-sensing element (device), connects the optical fiber A of coupling mechanism and temperature-sensing element (device) and is connected coupling mechanism and the optical fiber B of first photodiode; Reference path comprises the optical fiber that connects the coupling mechanism and second photodiode.
There is reflection unit in the optical fiber connector of described temperature-sensing element (device), and for example, reflection unit can be reflectance coating that is plated in the optical fiber connector end face or the grating that is engraved in optical fiber connector.
The light that light source sends is divided into two bundles that intensity equates through coupling mechanism: a branch of light arrives second photodiode through reference path; Another Shu Guang gets into temperature-sensing element (device) by optical fiber A, in the device reflection that is reflected of the end of temperature-sensing element (device), gets back to optical fiber A, and light intensity is modulated by the temperature field, gets into optical fiber B by coupling mechanism subsequently, arrives first photodiode through optical fiber B.
Reflective temperature sensor of the present invention also comprises signal output and control interface; Signal Processing and light source driving circuit are through signal output and control interface; Temperature value output with digital signal form; And, control the open and close of thermometric frequency, pattern and light source through signal output and the outside control signal of control interface reception.
The advantage and the good effect that the present invention is based on the reflective temperature sensor of optical fiber radiation induced attenuation temperature characterisitic are:
1. safe.Because not charged during the fiber work of temperature-sensing element (device), the luminous energy of system is faint, does not have potential safety hazard, can be used for inflammable explosive article storerooms such as oil depot.
2. anti-electromagnetic interference (EMI).Optical fiber itself is insulator, and its decay does not receive electromagnetic effect, so sensor of the present invention can be used under the abominable electromagnetic environment such as power industry.
3. the simple and flexible design of temperature-sensing element (device) manufacturing process.Temperature-sensing element (device) only needs to form with the optical fiber coiling behind the irradiation, does not have complicated structure, to the profile less-restrictive.Can reach different measuring accuracy and measurement ranges through technological factors such as adjustment irradiation dose, annealing temperature and optical fiber doping.
4. cost is relatively low.The fibre optic temperature sensor of relative other types, sensor of the present invention do not have complicated demodulating system and structure and special device, can adopt the light source and the photodetector that are operated in communication wavelength, make simply, thereby cost are relatively low.
5. than high measurement accuracy.Can realize being superior to 0.5 ℃ thermometric resolution.
Description of drawings
Fig. 1 is the one-piece construction synoptic diagram of fibre optic temperature sensor of the present invention.
Embodiment
To combine accompanying drawing and embodiment that the present invention is done further detailed description below.
As shown in Figure 1; A kind of reflection-type optical fiber temperature sensor based on optical fiber radiation induced attenuation temperature characterisitic that the specific embodiment of the invention provides comprises: be used to provide the light source 1 of light signal, the coupling mechanism 2 that is used for beam split, the optical fiber A3 that measures light path, the temperature-sensing element (device) 4 of measuring light path, the optical fiber B5 that measures light path, reference path 7, first photodiode 6, second photodiode 8, signal Processing and light source driving circuit 9 and signal output and control interface 10.
Like Fig. 1; Light source 1 connects coupling mechanism 2 through optical fiber; Coupling mechanism 2 connects first photodiode 6, second photodiode 8 and temperature-sensing element (device) 4 respectively through optical fiber; First photodiode 6 and second photodiode 8 are connected by electrical wiring to signal Processing and light source driving circuit 9 respectively, and signal Processing and light source driving circuit 9 connect signal output and control interface 10 and light source 1 through electric wire.The optical fiber that connects coupling mechanism 2 and temperature-sensing element (device) 4 is for measuring the optical fiber A3 of light path, and the optical fiber that connects the coupling mechanism 2 and first photodiode 6 is for measuring the optical fiber B5 of light path, and the optical fiber that connects the coupling mechanism 2 and second photodiode 8 is reference path 7.
Photodiode 6,8 is used for light signal is converted into electric signal.The effect of signal Processing and light source driving circuit 9 is that two path signal is carried out filtering, amplification, analog to digital conversion and mathematical operation; Convert temperature value to, and send to computing machine or other equipment that is attached thereto through signal output with control interface 10 with the form of digital signal.
Concrete, the light source 1 among Fig. 1 can adopt stablizes SLD (super-radiance light emitting diode), for example is operated in the stable SLD of communication band 1310nm or 1550nm, also can adopt LASER Light Source.Reference path 7 and optical fiber A3 and optical fiber B5 can adopt common communications optical fiber; Signal output and control interface 10 can adopt the RS232 serial ports.
Measure light path and adopt the optical fiber fabrication temperature-sensing element (device) of handling through radiation annealing 4, utilize the temperature characterisitic of its radiation induced attenuation that light intensity is modulated, the realization all-optical fiber temperature is measured.Through scribing grating at the optical fiber connector of temperature-sensing element (device) 4 or plating reflectance coating at the optical fiber connector end face; Form reflective structure; Be equivalent to the length of fiber that has increased temperature-sensing element (device) 4; The equivalent fiber lengths that makes temperature-sensing element (device) 4 is 2 times of same transmission-type structure, has improved thermometric sensitivity.
Concrete temperature-sensing element (device) 4 manufacturing process of measuring in the light path are following: 1. the doped fiber of choosing is carried out radiation treatment; The The high temperature anneal of 2. optical fiber behind the irradiation being carried out schedule time predetermined temperature makes it abundant annealing, promptly in temperature-measuring range under the constant temperature optical fiber attenuation change no longer in time; 3. scribe grating or end face plating reflectance coating endways at the end of optical fiber; 4. optical fiber is turned to temperature-sensing element (device).
Doping and irradiation dose and sensitive optical fibre length will influence the sensitivity and the measurement range of final sensor, thereby need the sensitivity of sensor as requested and the sensitive optical fibre length of measurement range and permission to choose.For example, if sensitivity is required very high and requires sensitive optical fibre length can choose the heavy dose of irradiation of Er-doped fiber more in short-term, measurement range is had relatively high expectations to choose phosphorus-doped optical fiber low dose irradiation.The temperature of The high temperature anneal will be higher than the upper limit of final sensor temperature measurement range, if for example the highest measurement temperature is 60 ℃, can adopt 70 ℃ to carry out annealing in process.
The principle of work of the embodiment that this method provides is: signal Processing and light source driving circuit 9 provide power drives for light source 1, and the light that light source 1 sends is divided into two bundles that intensity equates through coupling mechanism 2; A branch of entering reference path 7 arrives second photodiode 8 by passing light optical fiber, converts electric signal into and sends signal Processing and light source driving circuit 9 to; Another bundle light gets into measures light path; Get into temperature-sensing element (device) 4 by passing light optical fiber A3; At the end of temperature-sensing element (device) 4 be reflected film or optical grating reflection, get back to passing light optical fiber A3, light intensity is modulated by the temperature field; Get into by coupling mechanism 2 subsequently and pass light optical fiber 5, convert electric signal into by first photodiode 6 and send signal Processing and light source driving circuit 9 to.After signal Processing and light source driving circuit 9 pass through filtering, amplification, analog to digital conversion and mathematical operation with the two path signal that receives; Become temperature value and send to computing machine or other equipment that is attached thereto through signal output with control interface 10 with the form of digital signal, thus the demonstration and the record of realization temperature.Computing machine or other equipment also can transmit control signal the open and close etc. of the thermometric frequency of control system, pattern and light source through signal output and control interface 10.Temperature meter of the present invention utilizes the output signal of reference path to eliminate the influence that factors such as light source power fluctuation cause measurement result, makes temperature measurement result more accurate.
If the luminous power that second photodiode 8 receives is P
1(T), the luminous power that receives of first photodiode 6 is P
2(T), T representes temperature value.Corresponding luminous power is respectively P under 25 ℃
1(25) and P
2(25), can get the normalization decay A (T) of temperature-sensing element (device) 4:
The value of the normalization decay A (T) of the temperature-sensing element (device) 4 under 25 ℃ is 0dB.According to the normalization decay (using 25 ℃ of normalization equally) of the temperature-sensing element (device) 4 that obtains before the test and the relation of temperature T, optical fiber attenuation is transformed corresponding temperature value T at last:
Wherein, n is the fitting of a polynomial exponent number, k
nIt is n rank fitting coefficient.
The decay of f (A (T)) expression sensitive optical fibre is owing to by the temperature field modulation, present certain functional relation with temperature.Because the difference on the stress in optical fiber dopant species, concentration, the pulling process, irradiation dose, annealing temperature or the like the factor all can be brought influence to function f (A (T)), and can not guarantee on the technology that they are in full accord, can't draw k through Theoretical Calculation
nValue, therefore can only confirm k through fitting of a polynomial
nCarry out fitting of a polynomial and need obtain in the sensor measurement scope A (T) of temperature-sensing element (device) 4 under each standard temperature, and be transverse axis with it, temperature T is that the longitudinal axis carries out match, k
nIn match, be determined.The principle of match is in that to meet the requirements of under the measuring accuracy exponent number n low as much as possible.The purpose of carrying out fitting of a polynomial is to improve the non-linear influence that temperature sensor measurements is caused to a certain extent on the one hand, compensates manufacture craft on the other hand to the influence that sensor measurement brings, and is a process that temperature sensor is calibrated.Obviously owing to technologic difference, for two different sensors, k
nValue also can be different.Accomplish the k of calibration back equality right-hand member
nBecome known constant, thereby in the use of sensor, can calculate current temperature value T according to A (T).
Reflective temperature sensor based on optical fiber radiation induced attenuation temperature characterisitic provided by the invention: the first, utilize the temperature characterisitic of the radiation induced attenuation of optical fiber to carry out intensity modulated, realized higher measuring accuracy; The second, a kind of reflective measurement structure is proposed, improved thermometric sensitivity, increased the dirigibility of sensitive element design and use; The 3rd, be provided with reference path, compensated the influence of light source fluctuation to measurement result.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106297150A (en) * | 2016-08-05 | 2017-01-04 | 宫子涵 | A kind of tunnel temperature monitoring system and temperature monitoring method |
| CN108139275A (en) * | 2016-09-20 | 2018-06-08 | 卢玛赛恩斯科技控股股份有限公司 | Temperature probe |
| CN111307196A (en) * | 2020-03-20 | 2020-06-19 | 电子科技大学 | A radiation-resistant method and system for distributed electrothermal annealing and photothermal annealing |
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| CN1687725A (en) * | 2005-06-08 | 2005-10-26 | 北京航空航天大学 | Temperature sensor of polarization-preserving fiber in reflection type |
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| CN102539011A (en) * | 2011-12-23 | 2012-07-04 | 北京航空航天大学 | Temperature sensor based on phosphor-doped fiber radiation induced attenuation thermosensitivity |
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2012
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Patent Citations (5)
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| US6033108A (en) * | 1994-12-14 | 2000-03-07 | Mcdermott Technology, Inc. | Extended range fiber-optic temperature sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106297150A (en) * | 2016-08-05 | 2017-01-04 | 宫子涵 | A kind of tunnel temperature monitoring system and temperature monitoring method |
| CN108139275A (en) * | 2016-09-20 | 2018-06-08 | 卢玛赛恩斯科技控股股份有限公司 | Temperature probe |
| CN111307196A (en) * | 2020-03-20 | 2020-06-19 | 电子科技大学 | A radiation-resistant method and system for distributed electrothermal annealing and photothermal annealing |
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