CN111207857B - Method for measuring optical fiber length by using distributed optical fiber temperature sensor - Google Patents
Method for measuring optical fiber length by using distributed optical fiber temperature sensor Download PDFInfo
- Publication number
- CN111207857B CN111207857B CN202010047333.5A CN202010047333A CN111207857B CN 111207857 B CN111207857 B CN 111207857B CN 202010047333 A CN202010047333 A CN 202010047333A CN 111207857 B CN111207857 B CN 111207857B
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- temperature
- distribution curve
- channel
- temperature distribution
- 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
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K15/00—Testing or calibrating of thermometers
- G01K15/005—Calibration
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The invention relates to a method for measuring the length of an optical fiber by using a distributed optical fiber temperature sensor, which comprises the steps of locally heating the optical fiber to manufacture a temperature mutation area; determining a fiber reference length L1; respectively acquiring a first temperature distribution curve and a second temperature distribution curve of the optical fiber; in the temperature abrupt change region, a sliding window mechanism algorithm is adopted to calculate the correlation R of a temperature distribution curve I and a temperature distribution curve II2Obtaining a corresponding offset delta L to obtain a correlation distribution curve; finding a correlation maximum R in a correlation profile2 maxAnd obtaining the corresponding maximum offset DeltaLmaxCalculating the length of the optical fiber as L-L1-DeltaLmax. According to the invention, the temperature points measured from different two ends of the same optical fiber are overlapped by utilizing a double-channel loopback measurement mode, so that the accurate length of the optical fiber is obtained, the stability and the reliability of the long-distance optical fiber temperature measurement are improved, and the consistency of the temperature resolution of each point on the optical fiber is ensured.
Description
Technical Field
The invention relates to the technical field of optical fiber sensing, in particular to a method for measuring the length of an optical fiber by using a distributed optical fiber temperature sensor.
Background
The distributed optical fiber temperature sensor measures the temperature of each point along the optical fiber mainly according to the optical time domain reflection of the optical fiber and the back Raman scattering temperature effect of the optical fiber. The existing method for detecting the length of the optical fiber mainly adopts a single-channel mode for measurement, namely, only one end of the optical fiber is connected with the distributed optical fiber temperature sensor, and due to signal attenuation, the farther the optical fiber is away from the distributed optical fiber temperature sensor, the weaker the signal acquired by an optical receiver is, so that the length of the optical fiber is measured inaccurately, and the temperature resolution of the optical fiber is reduced along with the increase of the distance. Therefore, the prior art has yet to be developed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for accurately measuring the length of an optical fiber and improving the stability of the temperature resolution of each area of the optical fiber by using a distributed optical fiber temperature sensor.
In order to achieve the above purpose, the invention provides the following technical scheme:
the invention provides a method for measuring the length of an optical fiber by using a distributed optical fiber temperature sensor, which comprises the following steps:
heating the optical fiber locally to a designated value to manufacture a temperature mutation region;
connecting two ends of an optical fiber with a first channel and a second channel of a distributed optical fiber temperature sensor respectively, emitting laser pulses in the first channel or the second channel, collecting anti-stokes signals, and determining an optical fiber reference length L1 according to the anti-stokes signals;
emitting laser pulses in the first channel, acquiring Stokes signals and anti-Stokes signals of all points of the first channel, and calculating the ratio of the Stokes signals to the anti-Stokes signals of all points of the first channel to obtain a first temperature distribution curve of the optical fiber;
emitting laser pulses in the second channel, acquiring Stokes signals and anti-Stokes signals of all points of the second channel, and calculating the ratio of the Stokes signals to the anti-Stokes signals of all points of the second channel to obtain a second temperature distribution curve of the optical fiber;
respectively obtaining temperature abrupt change regions in the temperature distribution curve I and the temperature distribution curve II, and calculating the correlation R of the temperature distribution curve I and the temperature distribution curve II in the temperature abrupt change regions by adopting a sliding window mechanism algorithm2Obtaining the offset delta L of the first temperature distribution curve relative to the second temperature distribution curve to obtain a correlation distribution curve;
finding a correlation maximum R in a correlation profile2 maxAnd obtaining the corresponding maximum offset DeltaLmaxCalculating the length of the optical fiber as L-L1-DeltaLmax。
Further, at the maximum value of correlation R2 maxSelecting multiple points from left and right sides, and usingAnd fitting by using a least square method to obtain a fitting curve, and solving the peak position of the fitting curve.
Furthermore, a thermostat is arranged in the distributed optical fiber temperature sensor and close to the first channel and the second channel, a reference optical fiber and a thermometer are arranged in the thermostat, and the reference optical fiber is connected with an external optical fiber.
The technical scheme of the invention has the following beneficial effects:
according to the invention, the temperature distribution curves of the optical fiber are respectively obtained from two directions by utilizing a double-channel loopback measurement mode, and the two temperature distribution curves are integrated and aligned by adopting a sliding window mechanism algorithm, so that the temperature points measured from different two ends of the same optical fiber are overlapped, the accurate length of the optical fiber is further obtained, the stability and the reliability of the long-distance optical fiber temperature measurement are improved, and the consistency of the temperature resolution of each point on the optical fiber is ensured.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of the connection of the present invention;
FIG. 3 is a schematic diagram of a first temperature distribution curve and a second temperature distribution curve according to the present invention;
FIG. 4 is a diagram of a temperature distribution curve I and a temperature distribution curve II in a temperature mutation region according to the present invention;
FIG. 5 is a schematic illustration of a correlation profile of the present invention;
FIG. 6 is a schematic representation of a correlation profile of the present invention after least squares fitting;
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In the present invention, unless expressly stated or limited otherwise, the terms "connected," "secured," and the like are to be construed broadly, and for example, "connected" may be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.
Referring to fig. 1 to 6, the present invention provides a method for measuring a length of an optical fiber by using a distributed optical fiber temperature sensor, including the following steps:
heating the optical fiber locally to a designated value to manufacture a temperature mutation area, so as to facilitate the next measurement;
connecting two ends of an optical fiber with a first channel and a second channel of a distributed optical fiber temperature sensor respectively, emitting laser pulses in the first channel or the second channel, collecting anti-stokes signals, and determining an optical fiber reference length L1 according to the anti-stokes signals; because signals on the anti-stokes frequency are sensitive to the temperature on the optical fiber, when laser is transmitted in the optical fiber, reflected signals always return, the data acquisition card of the distributed optical fiber temperature sensor samples the anti-stokes signals at all times, when the laser is transmitted to the tail end of the optical fiber, no reflected signals exist, and the data acquisition card cannot acquire the anti-stokes signals, so that an obvious mutation position can be found on the whole data curve, the optical fiber reference length L1 can be determined according to the mutation position, and the L1 is configured in the distributed optical fiber temperature sensor in a mode of sending commands through a network.
Switching an optical switch of the distributed optical fiber temperature sensor to a first channel, emitting laser pulses in the first channel, acquiring stokes signals and anti-stokes signals of all points of the first channel, and calculating the ratio of the stokes signals to the anti-stokes signals of all points of the first channel to obtain a first temperature distribution curve (as shown in fig. 3) of the optical fiber;
switching an optical switch of the distributed optical fiber temperature sensor to a second channel, emitting laser pulses in the second channel, acquiring stokes signals and anti-stokes signals of all points of the second channel, and calculating the ratio of the stokes signals to the anti-stokes signals of all points of the second channel to obtain a second optical fiber temperature distribution curve (as shown in figure 3); because the signals at the stokes frequency are less sensitive to the temperature on the optical fiber, and the signals at the anti-stokes frequency are more sensitive to the temperature on the optical fiber, the signal intensity ratio of the two frequencies corresponds to the temperature change of the optical fiber, so that the temperature distribution curve of the optical fiber can be obtained according to the ratio of the stokes signal to the anti-stokes signal on the optical fiber.
Respectively obtaining temperature abrupt change regions (as shown in fig. 4) in the first temperature distribution curve and the second temperature distribution curve, and calculating the correlation R between the first temperature distribution curve and the second temperature distribution curve in the temperature abrupt change regions by adopting a sliding window mechanism algorithm2Obtaining an offset delta L of the first temperature distribution curve relative to the second temperature distribution curve to obtain a correlation distribution curve (as shown in FIG. 5); the temperature distribution curves measured from different ends of the same optical fiber are similar, but have a certain offset, so that the two temperature distribution curves need to be aligned through a sliding window mechanism algorithm. In this embodiment, the temperature distribution curve two is kept still, and the temperature distribution curve one is relative to the temperature distribution curve twoAnd moving, calculating the correlation between the first temperature distribution curve and the second temperature distribution curve once every time of moving, moving for multiple times to align the first temperature distribution curve and the second temperature distribution curve, counting all correlation results to obtain the correlation distribution curve of the first temperature distribution curve and the second temperature distribution curve, and obtaining the offset delta L of the first temperature distribution curve relative to the second temperature distribution curve.
The greater the correlation between the first temperature distribution curve and the second temperature distribution curve, the stronger the data match between the first channel and the second channel, and therefore the maximum value R of the correlation in the correlation distribution curve is found2 maxObtaining the best matching point of the first channel and the second channel data and obtaining the corresponding maximum offset DeltaLmaxFurther, the accurate optical fiber length L-L1- Δ L is obtainedmaxTherefore, the stability and the reliability of the long-distance optical fiber temperature measurement are improved, and the consistency of the temperature resolution of each point on the optical fiber is ensured.
In the embodiment, the optical fiber can be locally heated by the thermostat in a laboratory environment, the optical fiber can be wrapped by the towel in a field working environment, hot water is poured on the towel to manufacture a local high-temperature condition, and the operation is convenient.
In this embodiment, the measurement of the fiber reference length L1 is based on that there is no back-scattered signal after the laser is transmitted to the end of the optical fiber, after which the signal collected by the distributed optical fiber temperature sensor is substantially background noise, and after the de-noising process, an obvious boundary point can be found on the whole data curve, where the anti-stokes signal before the boundary point is a smooth curve, and the boundary point is followed by a straight line with an amplitude close to 0. The position from the start position to the demarcation point is the light reference length L1. The setting of the optical fiber reference length L1 greatly reduces the working time of the distributed optical fiber temperature sensor, and simultaneously ensures that the data deviation at the two ends of the optical fiber is within an effective range, and the smooth operation of the sliding window mechanism algorithm is ensured.
According to the invention, the temperature distribution curves of the optical fiber are respectively obtained from two directions by utilizing a double-channel loopback measurement mode, and the two temperature distribution curves are integrated and aligned by adopting a sliding window mechanism algorithm, so that the temperature points measured from different two ends of the same optical fiber are overlapped, the accurate length of the optical fiber is further obtained, the stability and the reliability of the long-distance optical fiber temperature measurement are improved, and the consistency of the temperature resolution of each point on the optical fiber is ensured.
Preferably, at the maximum value of the correlation R2 maxA plurality of points are selected, a fitting curve (as shown in fig. 6) is obtained by fitting with the least square method, and the peak position of the fitting curve is obtained. Since the resolution of the distributed optical fiber temperature sensor is fixed, each movement of the temperature profile one and the temperature profile two is a fixed distance, that is, the offset is a fixed value, the obtained correlation result is a discrete array, but the true best matching place may be within the offset, so that the obtained maximum value of the correlation and the maximum offset have errors. In the embodiment, a fitting curve is obtained from the discrete array by using the least square method, and the peak position of the fitting curve is found, so that a more accurate correlation maximum value R can be obtained2 maxAnd a maximum offset amount Δ LmaxFurther, the accurate optical fiber length is obtained, and errors are reduced.
Preferably, a thermostat is arranged in the distributed optical fiber temperature sensor and close to the first channel and the second channel, a reference optical fiber and a thermometer are arranged in the thermostat, and the reference optical fiber is connected with an external optical fiber. The Stokes signal and the anti-Stokes signal can generate different wavelength losses in a high-temperature environment, finally, temperature detection is inaccurate, and the drift of the optical fiber temperature in the high-temperature environment is effectively reduced by the arrangement of the thermostat, so that the stability and the accuracy of temperature detection of the distributed optical fiber temperature sensor are improved.
The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Not all embodiments are exhaustive. All obvious changes and modifications which are obvious to the technical scheme of the invention are covered by the protection scope of the invention.
Claims (3)
1. A method for measuring the length of an optical fiber using a distributed optical fiber temperature sensor, comprising the steps of:
heating the optical fiber locally to a designated value to manufacture a temperature mutation region;
connecting two ends of an optical fiber with a first channel and a second channel of a distributed optical fiber temperature sensor respectively, emitting laser pulses in the first channel or the second channel, collecting anti-stokes signals of all points on the optical fiber, and determining an optical fiber reference length L1 according to the anti-stokes signals;
emitting laser pulses in the first channel, acquiring Stokes signals and anti-Stokes signals of all points of the first channel, and calculating the ratio of the Stokes signals to the anti-Stokes signals of all points of the first channel to obtain a first temperature distribution curve of the optical fiber;
emitting laser pulses in the second channel, acquiring Stokes signals and anti-Stokes signals of all points of the second channel, and calculating the ratio of the Stokes signals to the anti-Stokes signals of all points of the second channel to obtain a second temperature distribution curve of the optical fiber;
respectively obtaining temperature abrupt change regions in the temperature distribution curve I and the temperature distribution curve II, and calculating the correlation R of the temperature distribution curve I and the temperature distribution curve II in the temperature abrupt change regions by adopting a sliding window mechanism algorithm2Obtaining the offset delta L of the first temperature distribution curve relative to the second temperature distribution curve to obtain a correlation distribution curve;
finding a correlation maximum R in a correlation profile2 maxAnd obtaining the corresponding maximum offset DeltaLmaxCalculating the length of the optical fiber as L-L1-DeltaLmax。
2. The method of claim 1, wherein the method further comprises measuring the length of the optical fiber with a distributed fiber optic temperature sensorCharacterised by a maximum value of the correlation R2 maxSelecting a plurality of points on the left and right sides, fitting by using a least square method to obtain a fitting curve, and solving the peak position of the fitting curve.
3. The method of claim 1, wherein an oven is disposed in the distributed optical fiber temperature sensor near the first and second channels, a reference optical fiber and a thermometer are disposed in the oven, and the reference optical fiber is connected to an external optical fiber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010047333.5A CN111207857B (en) | 2020-01-16 | 2020-01-16 | Method for measuring optical fiber length by using distributed optical fiber temperature sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010047333.5A CN111207857B (en) | 2020-01-16 | 2020-01-16 | Method for measuring optical fiber length by using distributed optical fiber temperature sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111207857A CN111207857A (en) | 2020-05-29 |
| CN111207857B true CN111207857B (en) | 2021-02-26 |
Family
ID=70784820
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010047333.5A Active CN111207857B (en) | 2020-01-16 | 2020-01-16 | Method for measuring optical fiber length by using distributed optical fiber temperature sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111207857B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111734391B (en) * | 2020-07-30 | 2023-03-21 | 国兴汇金(深圳)科技有限公司 | Online calibration method, system and storage medium for well depth and temperature of oil and gas well |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8520827D0 (en) * | 1985-08-20 | 1985-09-25 | York Ventures & Special Optica | Fibre-optic sensing devices |
| CN101629855B (en) * | 2008-07-18 | 2012-07-11 | 派克森公司 | Distributed optical fiber sensing system and detection method utilizing same |
| CN102322811B (en) * | 2011-08-10 | 2013-06-05 | 中国计量学院 | Chaotic laser relevant full-distribution fiber Raman and Rayleigh photon sensor |
| CN104344913A (en) * | 2014-10-09 | 2015-02-11 | 国家电网公司 | Temperature measurement system and method based on fiber grating sensing |
| CN209513088U (en) * | 2018-09-07 | 2019-10-18 | 中国南方电网有限责任公司超高压输电公司贵阳局 | Cable tunnel temperature monitoring system based on distributed optical fiber temperature measurement |
| CN110231106B (en) * | 2019-07-08 | 2020-10-09 | 安徽理工大学 | Temperature self-correction method for fitting attenuation difference of distributed optical fiber Raman temperature measurement system |
-
2020
- 2020-01-16 CN CN202010047333.5A patent/CN111207857B/en active Active
Non-Patent Citations (1)
| Title |
|---|
| 基于喇曼散射的分布式光纤温度传感器的温度修正;汤玉泉 等;《光子学报》;20150531;第44卷(第5期);0506006-1-0506006-5 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111207857A (en) | 2020-05-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108458814B (en) | Self calibration detection device and temperature demodulation method towards fiber Raman temperature-sensing system | |
| CN103017934B (en) | Self-correction method capable of eliminating wavelength dispersion of distributed Raman temperature measurement system | |
| CN110849501B (en) | Method for measuring and calibrating optical switch loss in distributed optical fiber temperature measuring device | |
| CN109029769A (en) | High-precision temperature demodulation method based on distributed fiber Raman sensing technology | |
| CN104864979A (en) | Correction method of errors measured by distributed raman optical fiber temperature measuring system | |
| CN111207854B (en) | Data processing algorithm based on distributed optical fiber temperature sensor | |
| KR20140051495A (en) | Method for improving optical time domain reflectometer(otdr) performance | |
| CN100549615C (en) | Measure the optics of optical transparent body and the method for physical thickness | |
| CN111207857B (en) | Method for measuring optical fiber length by using distributed optical fiber temperature sensor | |
| CN114838745B (en) | Single-data-channel multi-light-path parallel sensing method and system | |
| CN101794506B (en) | Method and device used for data calibration in distributed type optical fiber temperature sensor | |
| CN111795759A (en) | Method and system for dispersion correction of distributed Raman fiber temperature measurement system | |
| CN103353359B (en) | Distributed temperature-sensitive optical fiber one-point calibration method | |
| CN107782696A (en) | The sensor-based system and method for distributed liquid refractivity are measured using tapered fiber | |
| CN110375780A (en) | The method of the disconnected fine continued access measurement of OFDR | |
| JP7299584B2 (en) | SPECIAL OPTICAL FIBER FOR MEASURING THREE-DIMENSIONAL CURVE SHAPE AND MANUFACTURING METHOD THEREOF, AND SYSTEM FOR MEASURING THREE-DIMENSIONAL CURVE SHAPE USING SPECIAL OPTICAL FIBER | |
| CN112033572B (en) | Method for compensating bending loss and Stokes light and anti-Stokes light attenuation in optical time domain reflectometer | |
| CN106908800B (en) | Method for improving pulse ranging precision and pulse ranging equipment | |
| CN112964387B (en) | Demodulation method for temperature along optical fiber in Raman optical time domain reflectometer | |
| CN112697303B (en) | Distributed optical fiber sensing system and detection method for smart grid | |
| CN106353009B (en) | DTS system attenuation coefficient different time scales determine method | |
| CN104457583B (en) | A kind of optic fibre length measurer and method | |
| JP5687108B2 (en) | Displacement measurement system | |
| JPH01232228A (en) | Received signal processing method for optical fiber backward scattered light | |
| CN111060215A (en) | Method for detecting spatial resolution of distributed optical fiber temperature sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |