• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a distributed fiber-optic sensor based on Brillouin light scattering, with an optical fiber as a sensor, which can be used for measuring the distribution of mechanical stresses and / or temperature with high precision and spatial resolution. The sensor according to the invention comprises two sources of optical radiation (1, 2), an optical measuring fiber (3) and an optical radiation detector (4), the optical measuring fiber (3) having the first optical radiation source (1) and the optical radiation detector (4) ) is connected by a fiber optic transmission line, the length of which is at least half the length of the optical measuring fiber, and the fiber optic transmission line comprises two mutually isolated conduction paths (5, 6).
    公开号:CH714284B1
    申请号:CH00270/19
    申请日:2017-08-25
    公开日:2021-10-29
    发明作者:Nikolaevich Burov Vladimir；Vladimirovich Semenyuga Vyacheslav；Vladimirovna Zenkina Yana；Borisovich Zakharov Dmitriy；Ivanovich Perederiy Vyacheslav；Anatol'yevich Yakovlev Vadim
    申请人:Llc Tst Engineering Ul Moskovskaya；
    IPC主号:
    专利说明:

    The invention relates to distributed fiber optic sensors based on Brillouin light scattering, with optical fibers as sensors that can be used for measuring the distribution of mechanical stresses and / or temperature with high precision and spatial resolution.
    From the prior art, fiber optic sensors for measuring the distribution of such physical quantities such. B. temperature, deformation or hydrostatic pressure along a sensitive optical fiber are known, which function according to the principle of detecting the parameter distribution of the scattered radiation fine structure, namely the Brillouin light scattering, also called Brillouin-Mandelstam scattering. The location of the parameter measurement (pressure, deformation, temperature) is determined by converting the delay time between the scanning and the scatter signal detection into the distance that corresponds to the path of the light radiation in the optical fiber from the evaluation device to the scattering location and back.
    The measurement of the delay time can be done directly, such. B. in a known fiber optic Brillouin evaluation device (RU140707U1, published on May 20, 2014). In the known evaluation device, the method of Brillouin optical time domain analysis (BOTDA, Brillouin Optical Time Domain Analysis) based on the principles of optical time domain reflectometry (OTDR, Optical Time Domain Reflectometry) is used. In the known evaluation device, the delay time between the pulse of the optical radiation, which takes part in the Brillouin scattering, and the signal detected by the photocell, which is assigned to the Brillouin scattering and in the optical fiber in the direction that corresponds to the direction of the pulse is opposite, progresses.
    Another method for delay time measurement is known from the prior art (see, for example, European patent application EP 2110646 A2, published: December 11, 2013; Journal of Lightwave Technology, Vol. 15, No. 4, pp. 654 -662 1997, published 04.1997). In the known method, the method of Brillouin optical frequency domain analysis (BOFDA, Brillouin Optical Frequency Domain Analysis) based on the principles of optical frequency domain reflectometry (OFDR, Optical Frequency Domain Reflectometry) is used. In known devices, the dependence of the amplitude and phase of the optical signal associated with Brillouin scattering on the modulation frequency of one of the optical waves becomes. Then, using the Fourier transformation of the frequency dependency, the time dependency, which is analogous to the dependency detected by the Brillouin optical time domain analysis, is calculated.
    Brillouin scattering in the optical fiber can be viewed as the diffraction of light in a moving grating of the refractive index generated by the sound wave. The signal reflected back from the grating is Doppler shifted in frequency because the grating moves at the speed of sound. The speed of sound is directly linked to the material density and is dependent on the material temperature and the internal mechanical stress (deformation). So the size of the Brillouin offset contains the information about the temperature and deformation at the point of scattering. For precise deformation determination, the temperature measurement and subtraction of the temperature contribution in the Brillouin offset, i.e. temperature compensation, is required. When protecting the optical fiber from external mechanical influences, the Brillouin offset depends exclusively on the temperature. The measurement of the frequency Brillouin offset thus allows the temperature and the deformation to be measured.
    There are commercially available fiber-optic temperature and deformation sensors based on Brillouin light scattering (see e.g., URL: http://www.fibristerre.de/products-andservices/, retrieval date 13.05.2016; URL : http://www.neubrex.com/htm/products.htm, retrieval date 13/05/2016; URL: http://omnisens.ch/ditest/3511-ditest-aim.php, retrieval date 13/05/2016) are intended to detect leaks in pipelines and to be used in systems of soil movement, building condition, plant condition and transmission line control.
    The next technical solution (prototype) is a known distributed fiber optic sensor for deformation and / or temperature measurement (see RU2346235C2, published on 07/27/2008), in which the method of Brillouin scattering is used. The known sensor contains a source of the gradual optical (light) radiation for the formation of an optical pulse with gradual distribution of the light intensity increasing towards the center and a source of the uninterrupted light radiation for the formation of the uninterrupted light radiation. The sensor also contains sensitive optical fiber that picks up the optical pulse as probing light radiation, the uninterrupted light radiation being incident excitation radiation causing the Brillouin scattering between the probing light radiation and the light excitation radiation, and also the detector of the Brillouin scattering in the time domain for detecting the Brillouin attenuation area or the Brillouin amplification area of the light radiation emanating from the sensitive optical fiber and assigned to the Brillouin scattering. In the known sensor, the deformation within the sensitive optical fiber and / or the temperature of the sensitive optical fiber is measured using a specific spectrum of the Brillouin attenuation or Brillouin gain.
    The disadvantage of the known sensor is that it can not limit the fiber optic with the Brillouin scattering, so that the detector contains the signal associated with the Brillouin scattering, this scattering takes place in the whole sensitive optical fiber, which leads to Increasing the measurement time, reducing the signal / noise ratio and limiting the distance between the light sources / detector and the most distant section of the sensitive optical fiber.
    The sensor according to the invention achieves the following object: Improvement of the operational properties and ensuring measurements at a sufficiently large distance from sensor parts (light sources and detector) that are sensitive to the arrangement conditions.
    Technical result of the sensor - increasing the distance from the light sources and the detector to the most distant section of the sensitive optical fiber, reducing the measurement time, increasing the signal / noise ratio.
    This result is achieved in that the distributed fiber optic sensor for measuring the deformation and / or temperature according to the principle of Brillouin scattering, consisting of a source of the 1st optical radiation, a source of the 2nd optical radiation, more sensitive optical Fiber and the detector of optical radiation, whereby the 1st end of the sensitive optical fiber is connected to the source of the 1st optical radiation, the 2nd end of the sensitive optical fiber is connected to the source of the 2nd optical radiation, thus Brillouin scattering arises between the 1st and the 2nd optical radiation, and the detector is connected to the 1st end of the sensitive optical fiber for detecting the radiation that emanates from the sensitive optical fiber and is assigned to Brillouin scattering, the sensitive optical fiber with the source of the 1st optical radiation and with the detector of the optical radiation through the fiber optic transmission The length of the line is at least half the length of the sensitive optical fiber, the source of the 1st optical radiation being connected to the sensitive optical fiber or the sensitive optical fiber to the detector of the optical radiation being connected by 2 mutually isolated lines.
    The sensitive optical fiber can be connected to the fiber optic lines by an optical circulator.
    The deformation and / or the temperature can be measured using a specific spectrum of the Brillouin attenuation.
    The deformation and / or the temperature can be measured using a specific spectrum of the Brillouin gain.
    The source of the 1st optical radiation, the source of the 2nd optical radiation and the detector of the optical radiation can be accommodated in a common housing.
    The advantages and properties of the sensor according to the invention are explained with reference to the accompanying drawings. 1 shows the general functional diagram of the distributed fiber-optic sensor according to the invention for measuring the deformation and / or temperature according to the Brillouin scattering method.
    Distributed fiber optic sensor (Fig. 1) for measuring the deformation and / or temperature based on the Brillouin scattering, consisting of source 1 of the 1st optical radiation, source 2 of the 2nd optical radiation, sensitive optical fiber 3 and the detector 4 of the optical radiation.
    The 1st end of the sensitive optical fiber 3 is connected to the source 1 of the 1st optical radiation and the detector 4 of the optical radiation with a fiber optic transmission line, 2 mutually isolated transmission lines 5 and 6 are used. The connection can be carried out by an optical circulator 7.
    The source 1 of the 1st optical radiation, the source 2 of the 2nd optical radiation and the detector 4 of the optical radiation can be housed in a common housing 8, for. B. as it is known from the prior art for distributed fiber optic sensors.
    Distributed fiber optic sensor (Figure 1) works as follows.
    The source 1 sends the 1st optical radiation, which gets through the 1st fiber optic transmission line 5 and optical circulator 7 in the sensitive optical fiber 3 and propagates therein. Line 5 ensures the transmission of the first optical radiation with the required properties without interference. The source 2 emits the 2nd optical radiation, which gets into the sensitive optical fiber 3 and propagates in it counter to the 1st optical radiation. Sources 1 and 2 have properties that allow them to be used for corresponding Brillouin optical analysis. In the sensitive optical fiber 3, the Brillouin scattering occurs between the 1st and the 2nd optical radiation, as a result of which a signal is generated which is assigned to the Brillouin scattering that propagates in the sensitive optical fiber 3 and through the transmission line 6 hits the detector 4. Line 6 ensures the transmission of optical radiation with the required properties without interference. The sensitive optical fiber 3 can be connected to the fiber optic lines 5 and 6 through an optical circulator 7. Optical circulator 7 guides the 1st optical radiation from line 5 connected to source 1 into sensitive optical fiber 3 and the radiation from sensitive optical fiber 3 into line 6, which is connected to detector 4. The circulator 7 avoids the disturbing entry of the 1st optical radiation onto the detector 4, the entry of the radiation from the sensitive optical fiber 3 onto the source 1, and ensures the transmission of radiation from the sensitive optical fiber 3 to the detector 4 with low losses. Optical circulators are standard components and can be obtained from retailers (see e.g. URL: https://www.thorlabs.com/newgrouppage9.cfm objectgroup_id=373, access date 13.05.2016).
    Detector 4 detects the spectrum of the Brillouin attenuation or the Brillouin gain of the optical radiation that comes from the sensitive optical fiber 3 and is assigned to the Brillouin scattering, and determines the deformation and / or temperature of the sensitive optical fiber 3 based on a specific spectrum of the Brillouin attenuation or Brillouin gain.
    The local distribution of the measured variable along the sensitive optical fiber is determined according to the methods known from the prior art. In the sensor according to the invention, the Brillouin optical time domain analysis (BOTDA) method can be used if the 1st optical radiation is a pulse and the detector of the optical radiation detects the radiation emerging from the sensitive optical fiber and assigned to the Brillouin scattering as a function of the delay time in relation to the pulse of the 1st optical radiation. The distance to the measuring point is calculated based on the recalculation of the corresponding delay time. In this case, the sources 1, 2 and the detector 4 can be implemented in the same way as in the next technical solution (prototype).
    In the sensor according to the invention, the method of Brillouin optical frequency range analysis (BOFDA) can be used when the 1st optical radiation is harmonically modulated according to amplitude and the detector of the optical radiation the phase and the amplitude of the radiation depending on the modulation frequency the 1st optical radiation that emerges from the sensitive optical fiber and is assigned to Brillouin scattering. In this case, the sources 1, 2 and the detector 4 can be manufactured in the same way as in the commercial system using Brillouin scattering, which is known from the prior art. (see URL: http://www.fibristerre.de/products-andservices/, access date 13/05/2016).
    In the communications industry, fiber optic transmission lines are widely used for sending and receiving optical signals. A fiber optic transmission line is a combination of linear lines of fiber optic transmission systems with a common optical cable, linear facilities and maintenance facilities within the operating limits. Optical fibers are essential line components of a fiber optic transmission line. Optical fibers are characterized by the attenuation of the optical signal and the dispersion properties. The typical attenuation of radiation with a wavelength of 1550 nm in connected single-mode optical fibers is 0.19 to 0.22 dB / km, chromatic dispersion is about 20 ps / (nm · km). When optical radiation is transmitted along lines 5 and 6, the amplitude of the optical signal decreases due to the attenuation and the temporal waveform may be distorted due to the chromatic dispersion.
    In order to restore the amplitude of the optical signal in lines 5 and 6, optical amplifiers widely used in the communications industry can be used, for example erbium or Raman amplifiers, which are installed at a certain distance so that the gain value the total attenuation and compensates for the optical power loss in the previous section. The typical length of the line section without amplifier is 50 km, which corresponds to a loss of optical signal power of 10 dB.
    In addition to maintenance facilities (optical amplifiers) spectral optical filters can be used in lines 5 and 6, which filter the useful optical signal from the wavelength spectrum of the spectral noise of optical amplifiers, such as spontaneous emission of an erbium amplifier. To restore the temporal waveform of the signal, dispersion compensators (fiber or semiconductor compensators) can be used, which compensate for the dispersion accumulated in the previous section of the line. The use of optical fibers that support the polarization state of the signal makes it possible to avoid polarization mode dispersion and to reduce distortion in the transmission line. The combination of an optical amplifier with a series-connected dispersion compensator in the line constitutes a repeater which restores the shape of the signal transmitted via the line 6 to its original state, i.e. H. repeat the signal, can.
    It should be mentioned that in the line 6 no Brillouin scattering occurs, which is caused by the interaction of the 1st and 2nd optical radiation, which propagate against each other, since there is no 1st optical radiation in the opposite direction spreads. The use of the line 6 to connect the sensitive optical fiber 3 to the detector 4 thus prevents non-linear distortions of the transmitted optical radiation and limits the area in which the Brillouin scattering occurs except for the sensitive optical fiber 3.
    The length of the fiber optic transmission line is at least half that of the sensitive optical fiber 3. The length of the sensitive optical fiber 3 is denoted by L. If the length of the fiber optic transmission line is L / 2 (half the length of the sensitive optical fiber 3), the maximum distance to the most distant portion of the sensitive optical fiber 3 from the sources of optical radiation and from the detector 4 is 3L / 4 . If z. B. the sources of optical radiation 1, 2 and the detector 4 are housed in a common housing 8, this distance is achieved when the fiber optic transmission line and the sensitive optical fiber 3 are aligned so that the fiber optic transmission line with the sensitive optical fiber in the Distance L / 2 from the housing 8 is connected, the sensitive optical fiber additionally extends to L / 4 and is then fed back so that the remaining length 3L / 4 is sufficient for the connection with the source 1 and detector 4 housed in a common housing 8. If the fiber optic transmission line is missing, it is evident that the maximum possible distance to the most distant section of the sensitive optical fiber 3 from the sources of optical radiation 1, 2 and from the detector 4 is L / 2. So the increase in the above-mentioned distance when using line 6 is L / 4, i.e. H. 50% of L / 2. The choice of such a length of the fiber-optic transmission line therefore permits a substantial increase in the maximum possible distance between the most distant section of the sensitive optical fiber 3 and the sources of optical radiation 1, 2 / detector 4.
    An increase in the signal-to-noise ratio is achieved for sensors when measurements at a distance from optical radiation sources 1, 2 and the detector 4 are required, since the line 6 is the transmission of optical radiation from the sensitive optical fiber 3 to the detector 4 without the above-mentioned distortions that would arise when the radiation is transmitted in sensitive optical fibers. It should also be mentioned that the use of the circulator 7 prevents the radiation from the sensitive optical fiber 3 from entering the line 5, which prevents Brillouin scattering, which are propagated against each other by the interaction of the 1st and 2nd optical radiation arises, and thus enables the transmission of the 1st optical radiation from the source 1 to the sensitive optical fiber 3 without the above-mentioned distortions, whereby the signal-to-noise ratio is further increased.
    A reduction in the measurement time is achieved for sensors when measurements are required at a distance from the sources of the optical radiation 1, 2 and the detector 4, since no Brillouin scattering occurs in the line 5, so that by optical reflectometry analyzed fiber section is shortened down to sensitive optical fiber 3, whereby the measurement time - corresponding to the reduction of the transit time of the 1st optical radiation in sensitive optical fiber 3 from the fiber optic transmission line to the source 2 and back to the detector 4 - is reduced.
    It should also be mentioned that the typical maximum allowable length of the sensitive optical fiber does not exceed 50 km, so that the length of the fiber optic transmission line is not less than half the length of the sensitive optical fiber 3 obtained using standardized communication solutions can be easily implemented.
    权利要求:
    Claims (5)
    [1]
    1. Distributed fiber optic sensor for measuring the deformation and / or temperature according to the principle of Brillouin scattering, comprising a first optical radiation source (1) for generating a first optical radiation, a second optical radiation source (2) for generating a second optical radiation, an optical measuring fiber (3) and an optical radiation detector (4), a first end of the optical measuring fiber (3) being connected to the first optical radiation source (1), a second end of the optical measuring fiber (3) being connected to the second optical radiation source ( 2) is connected so that Brillouin scattering occurs between the first and second optical radiation, and the optical radiation detector (4) is assigned to the first end of the optical measuring fiber for detecting the radiation emanating from the optical measuring fiber and assigned to the Brillouin scattering is connected, characterized in that the optical measuring fiber (3) with the first optical radiation qu elle (1) and is connected to the optical radiation detector (4) by a fiber optic transmission line, the length of which is at least half the length of the optical measuring fiber, the first optical radiation source (1) with the optical measuring fiber (3) and the optical Measuring fiber (3) are connected to the optical radiation detector (4) by two mutually isolated conduction paths (5, 6) of the fiber-optic transmission line.
    [2]
    2. Distributed fiber optic sensor according to claim 1, characterized in that the optical measuring fiber (3) is connected to the two conduction paths (5, 6) of the fiber optic transmission line by an optical circulator (7).
    [3]
    3. Distributed fiber optic sensor according to claim 1, characterized in that the deformation and / or temperature is measured using a specific spectrum of the Brillouin attenuation.
    [4]
    4. Distributed fiber optic sensor according to claim 1, characterized in that the deformation and / or temperature is measured using a specific spectrum of the Brillouin gain.
    [5]
    5. Distributed fiber optic sensor according to claim 1, characterized in that the first optical radiation source (1), the second optical radiation source (2) and the optical radiation detector (4) are accommodated in a common housing.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    KR0133488B1|1993-01-06|1998-04-23|Toshiba Kk|Temperature distribution detector using optical fiber|
    RU2082119C1|1994-05-20|1997-06-20|Московский государственный университет леса|Fiber-optical multiplexer which measures temperature|
    DE102008019150B4|2008-04-16|2010-07-08|BAM Bundesanstalt für Materialforschung und -prüfung|Apparatus and method for Brillouin frequency domain analysis|
    WO2010061718A1|2008-11-27|2010-06-03|ニューブレクス株式会社|Distributed optical fiber sensor|
    RU2510609C2|2012-07-27|2014-04-10|Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Московский государственный технический университет имени Н.Э. Баумана" |Apparatus for optical identification of measurement channels of built-in nondestructive inspection system based on fibre-optic bragg sensors|CN110361111B|2019-08-15|2021-11-26|广东电网有限责任公司|Temperature precision testing system and method for distributed optical fiber temperature sensor|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    RU2016135839|2016-09-06|
    PCT/RU2017/000621|WO2018048327A1|2016-09-06|2017-08-25|Distributed fibre optic sensor|
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