CN210981350U - Distributed optical fiber humidity and temperature simultaneous detection device - Google Patents
Distributed optical fiber humidity and temperature simultaneous detection device Download PDFInfo
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- CN210981350U CN210981350U CN201922165387.7U CN201922165387U CN210981350U CN 210981350 U CN210981350 U CN 210981350U CN 201922165387 U CN201922165387 U CN 201922165387U CN 210981350 U CN210981350 U CN 210981350U
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 86
- 238000001514 detection method Methods 0.000 title claims abstract description 42
- 238000001914 filtration Methods 0.000 claims abstract description 7
- 239000000835 fiber Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 13
- 239000000523 sample Substances 0.000 claims description 8
- 238000001228 spectrum Methods 0.000 claims description 6
- 239000004642 Polyimide Substances 0.000 claims description 4
- 229920001721 polyimide Polymers 0.000 claims description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 3
- 238000005259 measurement Methods 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000009529 body temperature measurement Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 101150102131 smf-1 gene Proteins 0.000 description 2
- 238000001069 Raman spectroscopy Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000010259 detection of temperature stimulus Effects 0.000 description 1
- 230000004807 localization Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000000253 optical time-domain reflectometry Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000026041 response to humidity Effects 0.000 description 1
- 230000006903 response to temperature Effects 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
A distributed optical fiber humidity and temperature simultaneous detection device comprises a narrow-linewidth light source, a first coupler, a pulse modulator, an optical fiber amplifier, a second coupler, a sensing optical fiber, a photoelectric detection and filter circuit, a frequency mixer, a frequency scanner and a digital signal processor; the narrow-linewidth light source is connected with the input end of the first coupler, one output end of the first coupler is connected with the optical fiber amplifier through the pulse modulator, and the other output end of the first coupler is connected with one input end of the photoelectric detection and filter circuit; the output end of the optical fiber amplifier is connected with the input end of the sensing optical fiber through a second coupler, and the input end of the sensing optical fiber is connected with the other input end of the photoelectric detection and filtering circuit through one output end of the second coupler; the output end of the photoelectric detection and filter circuit is connected with the input end of the frequency mixer; the frequency scanner is connected with the frequency mixer; the output end of the frequency mixer is connected with the digital signal processor, and finally, the distribution information of the temperature and the humidity of the space where the sensing optical fiber is located is obtained through calculation.
Description
Technical Field
The utility model relates to a humidity and temperature simultaneous detection field under on a large scale, the distributed environment especially relates to a distributed optical fiber humidity and temperature simultaneous detection device.
Background
The traditional method for obtaining the environmental humidity based on the change of the refractive index of the material outside the optical fiber, which causes the change of the characteristics (such as transmission constant, phase or intensity) of the optical signal transmitted in the optical fiber, can generally only measure the humidity of a single point or a local part. As the common method for coating the polyimide material (PI) on the surface of the Fiber Bragg Grating (FBG), the PI material expands along with the change of humidity to cause the fiber strain to cause the central wavelength of the FBG to change; another common humidity detection method is to utilize light to pass through a space containing water vapor to cause a change in phase or intensity, and then calibrate the humidity detection method to measure the humidity. The common humidity measurement methods need to design and manufacture optical fiber sensing probes respectively, and have the defects of complex probe manufacturing process, long time, high cost, difficulty in multiplexing of an interference probe, difficulty in multi-point measurement and the like. In addition, since ambient temperature also has an effect on the measurement results, a temperature measurement element needs to be built into the humidity sensor head, increasing the complexity and cost of the sensor head.
In recent years, distributed strain and temperature measurements using brillouin scattering in optical fibers have received much attention. However, a distributed humidity sensor based on brillouin scattering and PI coating has not been reported, and how to eliminate the influence of temperature on the result in the distributed humidity measurement process needs to be solved urgently. In distributed optical fiber strain measurement, an optical fiber which is not affected by stress and only responds to temperature is generally arranged in parallel near a strain sensing optical fiber, and the measurement is generally realized by arranging another set of temperature sensing detection system based on the raman effect in the optical fiber. Because the temperature compensation scheme needs to lay another temperature sensing optical fiber and adopt a corresponding detection instrument, the software and hardware cost and complexity of the system are increased.
Disclosure of Invention
An object of the utility model is to solve the above-mentioned problem among the prior art, provide a distributing type optic fibre humidity and temperature detection device simultaneously, with the sensitive single mode fiber of humidity and the insensitive single mode fiber butt fusion in turn of humidity form sensing optical fiber, realize the humidity and the temperature simultaneous measurement of distributing type.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a distributed optical fiber humidity and temperature simultaneous detection device comprises a narrow-linewidth light source, a first coupler, a pulse modulator, an optical fiber amplifier, a second coupler, a sensing optical fiber, a photoelectric detection and filter circuit, a frequency mixer, a frequency scanner and a digital signal processor;
the light source output end of the narrow-linewidth light source is connected with the input end of a first coupler, one output end of the first coupler is connected with the optical fiber amplifier through a pulse modulator, and the other output end of the first coupler is connected with one input end of the photoelectric detection and filtering circuit; the narrow linewidth light source is used for emitting light with a frequency v0And split into probe light and reference light by the first coupler;
the output end of the optical fiber amplifier is connected with the input end of the sensing optical fiber through a second coupler, and the input end of the sensing optical fiber is connected with the other input end of the photoelectric detection and filtering circuit through one output end of the second coupler; when the probe light enters the sensing optical fiber region and Brillouin scattering occurs in the sensing optical fiber, Brillouin backscattering light generates Brillouin frequency shift v relative to incident lightB(ii) a The photoelectric detection and filter circuit is used for carrying out heterodyne detection on the Brillouin backscatter light and the reference light, further amplifying heterodyne detection signals, and removing direct-current components and higher harmonics through the filter circuit to obtain a difference frequency term v0-vB；
The output end of the photoelectric detection and filter circuit is connected with the input end of the frequency mixer; the frequency mixer is used for converting a difference frequency term v0-νBMixing with a signal generated by a microwave frequency source to obtain a baseband signal;
the frequency scanner is connected with the frequency mixer and is used for continuously changing the frequency of the microwave frequency source to construct a Brillouin spectrum; the output end of the frequency mixer is connected with a digital signal processor, and the digital signal processor is used for performing Lorentz curve fitting on the Brillouin spectrum to calculate vBAnd the distribution information of the temperature and the humidity of the space where the sensing optical fiber is located is obtained through calculation.
The sensing optical fiber is provided with a plurality of sections of humidity-sensitive single-mode optical fibers and humidity-insensitive single-mode optical fibers which are arranged at intervals, and the humidity-sensitive single-mode optical fibers and the humidity-insensitive single-mode optical fibers are alternately welded.
The outer surface of the humidity-sensitive single-mode optical fiber is coated with a polyimide material.
The humidity-sensitive single-mode optical fiber is coated with an acrylate material on the outer surface.
Compared with the prior art, the utility model discloses technical scheme obtains beneficial effect is:
the utility model discloses a detect the brillouin scattering signal of transmission in the ordinary single mode fiber of humidity sensitive material (like polyimide or other materials) coating, obtain on a large scale, the humidity information of high spatial distribution rate, for solving the influence of ambient temperature to humidity signal, nevertheless only to the single mode fiber segmentation butt fusion in turn of temperature sensitivity with the coating of humidity sensitive material's single mode fiber and conventional material, realize the humidity and the temperature simultaneous measurement of distributing type.
Drawings
Fig. 1 is a schematic structural view of the present invention;
fig. 2 is a graph showing changes in brillouin frequency shift of SMF and PI-SMF fibers when the temperature is constant at 50 ℃ and the humidity changes by 30% with respect to an initial value H0;
fig. 3 shows the change in brillouin shift of the SMF and PI-SMF fibers when humidity is constant at 40% RH and temperature changes at 40 deg.c from the initial value T0.
Detailed Description
In order to make the technical problem, technical solution and beneficial effects to be solved by the present invention clearer and more obvious, the following description is made in detail with reference to the accompanying drawings and embodiments.
As shown in fig. 1, the present embodiment includes a narrow line width light source, a first coupler, a pulse modulator, a fiber amplifier, a second coupler, a sensing fiber, a photo detection and filter circuit, a mixer, a frequency scanner, and a digital signal processor;
the light source output end of the narrow-linewidth light source is connected with the input end of a first coupler, one output end of the first coupler is connected with the optical fiber amplifier through a pulse modulator, and the other output end of the first coupler is connected with one input end of the photoelectric detection and filtering circuit; the output end of the optical fiber amplifier is connected with the input end of the sensing optical fiber through a second coupler, and the input end of the sensing optical fiber is connected with the other input end of the photoelectric detection and filtering circuit through one output end of the second coupler; the output end of the photoelectric detection and filter circuit is connected with the input end of the frequency mixer; the frequency scanner is connected with a mixer, and the output end of the mixer is connected with a digital signal processor.
The narrow linewidth light source emits light with a frequency v0Light with the wavelength of 1.55um is divided into detection light and reference light through a first coupler; the pulse modulator is used for amplifying the signal power to a proper value by adopting an optical fiber amplifier (EDFA) after pulse modulation is carried out on the detection light; when the probe light enters the sensing optical fiber region and Brillouin scattering occurs in the sensing optical fiber, Brillouin backscattering light generates Brillouin frequency shift v relative to the original incident lightB(ii) a The Brillouin backscatter light and the reference light are heterodyne-detected by a photoelectric detection circuit, and then heterodyne detection signals are further amplified, and direct current components and higher harmonics are removed by a filter circuit to obtain a difference frequency term v0-vB(ii) a The difference frequency term v0-vBMixing the signal generated by the microwave frequency source with the frequency of the mixer again to obtain a baseband signal; the Brillouin spectrum can be constructed by continuously changing the frequency of the microwave frequency source through the frequency scanner, and finally the Brillouin spectrum is subjected to Lorentz curve fitting through the digital signal processor to obtain vB。
The sensing optical fiber is provided with a plurality of sections of humidity-sensitive single-mode optical fibers and humidity-insensitive single-mode optical fibers which are arranged at intervals, and the humidity-sensitive single-mode optical fibers and the humidity-insensitive single-mode optical fibers are alternately welded.
Within the allowable range of the precision of the detection circuit device, the lengths of the single sections of the humidity-sensitive single-mode optical fiber and the humidity-insensitive single-mode optical fiber are as small as possible, and the simultaneous detection of the distributed environment humidity and temperature with high spatial resolution can be realized; in this embodiment, the optical fiber sensing is a continuous sensing optical fiber formed by alternately fusing a single-mode fiber (PI-SMF) sensitive to humidity (such as PI coating) and a single-mode fiber (SMF) insensitive to humidity (such as acrylate coating), each of which has a length of 4 m.
According to the method, the long-distance sensing optical fiber is manufactured, the detection device is built, and after calibration, distributed detection of temperature and humidity can be achieved. The precision and the spatial resolution of distributed optical fiber temperature and humidity sensing measurement can be improved by selecting smaller optical fiber length and adopting high-performance device components.
The utility model discloses a detection principle as follows:
1. the Brillouin scattering frequency shift of light transmitted in the single-mode optical fiber is related to the temperature and the strain of the single-mode optical fiber, and the change of the environmental humidity can cause the change of the strain of the PI-coated single-mode optical fiber, so that the temperature and the humidity information of the position of the sensing optical fiber can be obtained by respectively measuring the Brillouin frequency shift of the single-mode optical fiber coated with and uncoated with PI materials; spatial localization of temperature or humidity changes may be achieved by optical time domain reflectometry techniques. Specifically, in this embodiment, after absorbing moisture and expanding, the PI film coated on the surface of the single-mode optical fiber generates a stress acting on the single-mode optical fiber, so that the single-mode optical fiber generates a strain, which causes a corresponding brillouin frequency shift in the scattered light signal; and the frequency of scattered light of the single-mode optical fiber coated with the humidity-insensitive material does not change when the humidity changes. Therefore, the distribution information of the temperature and the humidity of the space where the sensing optical fiber is located can be obtained by detecting the Brillouin scattering signals of different positions and different optical fibers.
2. The brillouin frequency shift response to temperature and humidity of the two single mode fibers (SMF and PI-SMF) alternately connected in this embodiment are shown in fig. 2 and 3, respectively. The frequency shift of SMF is sensitive only to temperature and not to humidity changes; PI-SMF responds to both temperature and humidity changes. Therefore, according to different response coefficients of Brillouin frequency shifts of the SMF and the PI-SMF to temperature and humidity, which are obtained in advance, a simultaneous equation of the frequency shift changing along with the temperature and the humidity can be established. In practical application, the ambient temperature and humidity can be obtained by detecting the Brillouin frequency shift delta v of each section of single-mode optical fiber. The frequency shift of two adjacent sections of single-mode fibers SMF and PI-SMF used in this embodiment has the following relationship with temperature and humidity:
Δv1＝CT1ΔT+CH1ΔH
Δv2＝CT2ΔT+CH2ΔH
wherein Δ v1 and Δ v2 are the changes in Brillouin frequency shift with temperature and humidity, C, of SMF1 and PI-SMF1, respectivelyT1And CH1Temperature and humidity coefficients, C, of SMF1, respectivelyT2And CH2Respectively represent the temperature coefficient and the humidity coefficient of PI-SMF1, and respectively represent the variation of the temperature coefficient and the humidity coefficient relative to the initial values T0 and H0. The actual temperature T and the relative humidity H can be calculated by T-T0 + Δ T, H-H0 + Δ H. Consequently the utility model discloses a sensing optical fiber can obtain simultaneously on a large scale, the real-time temperature and the humidity information that changes of high spatial resolution.
Claims (4)
1. The utility model provides a distributing type optic fibre humidity and temperature detection device simultaneously which characterized in that: the device comprises a narrow-linewidth light source, a first coupler, a pulse modulator, an optical fiber amplifier, a second coupler, a sensing optical fiber, a photoelectric detection and filter circuit, a frequency mixer, a frequency scanner and a digital signal processor;
the light source output end of the narrow-linewidth light source is connected with the input end of a first coupler, one output end of the first coupler is connected with the optical fiber amplifier through a pulse modulator, and the other output end of the first coupler is connected with one input end of the photoelectric detection and filtering circuit; the narrow linewidth light source is used for emitting light with a frequency v0And split into probe light and reference light by the first coupler;
the output end of the optical fiber amplifier is connected with the input end of the sensing optical fiber through a second coupler, and the input end of the sensing optical fiber is connected with the other input end of the photoelectric detection and filtering circuit through one output end of the second coupler; when the probe light enters the sensing optical fiber region and Brillouin scattering occurs in the sensing optical fiber, Brillouin backscattering light generates Brillouin frequency shift v relative to incident lightB(ii) a The photoelectric detection and filter circuit is used for carrying out heterodyne detection on the Brillouin backscatter light and the reference light, further amplifying heterodyne detection signals and removing direct current components through the filter circuitThe higher harmonic wave is divided to obtain the difference frequency item v0-vB；
The output end of the photoelectric detection and filter circuit is connected with the input end of the frequency mixer; the frequency mixer is used for converting a difference frequency term v0-νBMixing with a signal generated by a microwave frequency source to obtain a baseband signal;
the frequency scanner is connected with the frequency mixer and is used for continuously changing the frequency of the microwave frequency source to construct a Brillouin spectrum; the output end of the frequency mixer is connected with a digital signal processor, and the digital signal processor is used for performing Lorentz curve fitting on the Brillouin spectrum to calculate vBAnd the distribution information of the temperature and the humidity of the space where the sensing optical fiber is located is obtained through calculation.
2. The apparatus of claim 1, wherein: the sensing optical fiber is provided with a plurality of sections of humidity-sensitive single-mode optical fibers and humidity-insensitive single-mode optical fibers which are arranged at intervals, and the humidity-sensitive single-mode optical fibers and the humidity-insensitive single-mode optical fibers are alternately welded.
3. The apparatus of claim 2, wherein the apparatus comprises: the outer surface of the humidity-sensitive single-mode optical fiber is coated with a polyimide material.
4. The apparatus of claim 2, wherein the apparatus comprises: the humidity-sensitive single-mode optical fiber is coated with an acrylate material on the outer surface.
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| CN201922165387.7U CN210981350U (en) | 2019-12-06 | 2019-12-06 | Distributed optical fiber humidity and temperature simultaneous detection device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110887527A (en) * | 2019-12-06 | 2020-03-17 | 厦门大学 | Distributed optical fiber humidity and temperature simultaneous detection device and detection method |
| US20220026287A1 (en) * | 2020-07-23 | 2022-01-27 | The Government Of The United States Of America, As Represented By The Secretary Of The Navy | Suppression of noise and cross-talk in brillouin fiber sensors |
| CN114755202A (en) * | 2022-06-15 | 2022-07-15 | 中国空气动力研究与发展中心设备设计与测试技术研究所 | Polyimide optical fiber distributed humidity sensor and positioning detection method |
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2019
- 2019-12-06 CN CN201922165387.7U patent/CN210981350U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110887527A (en) * | 2019-12-06 | 2020-03-17 | 厦门大学 | Distributed optical fiber humidity and temperature simultaneous detection device and detection method |
| CN110887527B (en) * | 2019-12-06 | 2024-06-11 | 厦门大学 | Device and method for simultaneously detecting humidity and temperature of distributed optical fibers |
| US20220026287A1 (en) * | 2020-07-23 | 2022-01-27 | The Government Of The United States Of America, As Represented By The Secretary Of The Navy | Suppression of noise and cross-talk in brillouin fiber sensors |
| US11473983B2 (en) * | 2020-07-23 | 2022-10-18 | The Government of the United States of America, as represented by the Secretarv of the Navy | Suppression of noise and cross-talk in brillouin fiber sensors |
| CN114755202A (en) * | 2022-06-15 | 2022-07-15 | 中国空气动力研究与发展中心设备设计与测试技术研究所 | Polyimide optical fiber distributed humidity sensor and positioning detection method |
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