CN201476903U - Serial-connection FBG (fiber Bragg grating) high sensitiveness temperature sensor - Google Patents

Serial-connection FBG (fiber Bragg grating) high sensitiveness temperature sensor Download PDF

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Publication number
CN201476903U
CN201476903U CN2009201728805U CN200920172880U CN201476903U CN 201476903 U CN201476903 U CN 201476903U CN 2009201728805 U CN2009201728805 U CN 2009201728805U CN 200920172880 U CN200920172880 U CN 200920172880U CN 201476903 U CN201476903 U CN 201476903U
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China
Prior art keywords
connection
fbg
metal
serial
temperature sensor
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Expired - Fee Related
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CN2009201728805U
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Chinese (zh)
Inventor
李阔
周振安
刘爱春
王秀英
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Institute of Crustal Dynamics of China Earthquake Administration
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Institute of Crustal Dynamics of China Earthquake Administration
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Abstract

The measurement result is affected seriously if the connection part of the dual metal FBG sensor has sliding situation during measurement process. For reducing the influence, the utility model adopts a serial-connection structure, namely the middle part of a metal base is fixed with the middle part of a metal long strip, two gratings are respectively connected between the ends of the metal base and the metal strip to form two measurement points. In this way, when a certain connection part has sliding situation, the observed values of the two measurement points are inconsistent; when no sliding situation occurs in all the connection parts, and the temperature is changed, the observed values of the two measurement points are consistent. Thereby, the serial-connection FBG (fiber Bragg grating) high sensitiveness temperature sensor can judge if the connection part has sliding situation.

Description

A kind of tandem fiber grating high sensitivity temperature sensor
One, technical field
The utility model relates to Fibre Optical Sensor, especially fiber-optical grating temperature sensor.
Two, technical background
Fiber grating has the incomparable advantage of many other sensors: full photo measure at the on-the-spot no electrical equipment of monitoring, is not disturbed by electromagnetism and nuclear radiation; There is not drift zero point, long-term stability; Measured with catoptrical centre wavelength sign, be not subjected to the influence of factors such as light source power fluctuation, optical fiber micro-bending effect and coupling loss; Absolute magnitude is measured, and need not calibration in system's installation and the long-term use; Long service life or the like.
Fiber grating is a photosensitivity of utilizing fiber optic materials, be that extraneous incident photon and fibre core interact and cause the permanent change of latter's refractive index, with the space phase grating that the Ultra-Violet Laser method of writing direct forms, its essence is the light filter or the catoptron that in fibre core, form an arrowband in the fibre core of single-mode fiber.Fiber grating belongs to the reflection-type device work, when the continuous wide band light that sends when light source is injected by Transmission Fibers, and it and grating generation coupling, this broadband light of grating pair is the corresponding narrow band light of reflected back selectively, and returns along former Transmission Fibers; The then direct transmissive of all the other broadband light.The centre wavelength value of the narrow band light of reflected back (also being the Bragg wavelength) is:
λ B=2n effΛ
In the following formula, n EffBe the effective reflection coefficient of FBG, Λ is the geometric distance between adjacent two barriers of FBG.When temperature variation, cause that the sensitivity of returning wavelength variable quantity relative temperature variable quantity is:
Δλ B/ΔT=[(1-P e)ε+ζ]λ B (1)
Wherein, P eValid round light constant for FBG; ε is that unit temperature changes the dependent variable of FBG down; ζ is the thermo-optical coeffecient of FBG.
The intrinsic temperature resolution of FBG is very low, about 0.1 ℃/pm.This all can't meet the demands in a lot of applications.Therefore, a lot of researchists just improve its temperature control and have done a lot of work.The principle of FBG temperature sensor enhanced sensitivity is to utilize FBG to temperature and the responsive simultaneously characteristic of strain, by reasonable structural design, FBG is in the same place with the high thermal expansion coefficient material package.When dut temperature changed, the deformation by the high thermal expansion coefficient material applied a dependent variable to FBG, made the wavelength variable quantity of returning of FBG strengthen.At first, the researchist is by directly sticking on FBG the enterprising trip temperature enhanced sensitivity of big expansion coefficient material.The effect of enhanced sensitivity that this method obtains is limited, is subjected to the restriction of material coefficient of thermal expansion coefficient.In March, 1999, people such as Jeahooh Hung have proposed to realize temperature sensitizing by thermometal that effect is obvious on Applied Optics periodical.Bi-metal temperature enhanced sensitivity principle: during temperature variation, the difference of the different metal length variable quantity of two kinds of thermal expansivity is changed into the variable quantity of grating length, make the variable quantity that returns centre wavelength of fiber grating increase.
Three, utility model content
In measuring process, if producing, the junction of thermometal fiber-optic grating sensor slides, will have a strong impact on measurement result.In order to reduce its influence, the utility model has been taked a kind of in-line structure, promptly the rectangular middle part of the middle part of metallic substrates and metal is fixed together, and respectively connects a grating between their end points, forms two measurement points, as shown in drawings.Like this, when certain junction took place to slide, the observed reading of two measurement points can be inconsistent; Do not slide when all junctions all, and temperature is when changing the observed reading unanimity of two measurement points.Therefore, this sensor can judge whether the junction slip has taken place.
The utility model provides a kind of tandem fiber grating high sensitivity temperature sensor, comprises that having thermal expansivity is α 1Metab, to have thermal expansivity be α 2Rectangular and two gratings of metal, the rectangular middle part of the middle part of described metab and described metal is fixed together, the two ends of described grating be separately fixed at described metab and described metal rectangular on.
Four, description of drawings
Accompanying drawing is a structural representation of the present utility model.
Wherein, 1 is grating, and 2 is metab, and 3 is that metal is rectangular, and 4 is point of fixity.
Five, specific embodiments
Below in conjunction with for example the utility model being done more detailed description:
This sensor is mainly by forming with the lower part: two gratings, to have thermal expansivity be α 1Metab and to have thermal expansivity be α 2Metal rectangular, the rectangular middle part of the middle part of metallic substrates and metal is fixed together, and respectively connects a grating between their end points, forms two measurement points, as shown in drawings.According to the sensitivity of sensor design, select α 1, α 2, grating length, the length that metab length and metal are rectangular; According to the working temperature interval of sensor design, the pre-loose length or the pre-stretching strain of two gratings are set.Control pre-loose length and pre-stretching strain for convenience, can take the method shown in patent 200810105788.7, it is rectangular to add the metal that has strip hole at the tie point of grating and base.In order to use under anti-riot occasion, the metal material of sensor also can replace with nonmetallic materials.
After sensor was installed, when certain junction took place to slide, the observed reading of two measurement points can be inconsistent; Do not slide when all junctions all, and temperature is when changing the observed reading unanimity of two measurement points.Therefore, this sensor can judge whether the junction slip has taken place, and by data analysis, draws more reliable result.

Claims (1)

1. a fiber grating high sensitivity temperature sensor comprises that having thermal expansivity is α 1Metab, to have thermal expansivity be α 2Rectangular and two gratings of metal, it is characterized in that: the rectangular middle part of the middle part of described metab and described metal is fixed together, the two ends of described grating be separately fixed at described metab and described metal rectangular on.
CN2009201728805U 2009-08-19 2009-08-19 Serial-connection FBG (fiber Bragg grating) high sensitiveness temperature sensor Expired - Fee Related CN201476903U (en)

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Application Number Priority Date Filing Date Title
CN2009201728805U CN201476903U (en) 2009-08-19 2009-08-19 Serial-connection FBG (fiber Bragg grating) high sensitiveness temperature sensor

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102798484A (en) * 2012-08-14 2012-11-28 广东电网公司佛山供电局 Low-hysteresis fiber bragg grating temperature sensor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102798484A (en) * 2012-08-14 2012-11-28 广东电网公司佛山供电局 Low-hysteresis fiber bragg grating temperature sensor
CN102798484B (en) * 2012-08-14 2014-06-25 广东电网公司佛山供电局 Low-hysteresis fiber bragg grating temperature sensor

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