WO2021232196A1 - 光纤传感器以及利用该光纤传感器进行位置检测的方法 - Google Patents

光纤传感器以及利用该光纤传感器进行位置检测的方法 Download PDF

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WO2021232196A1
WO2021232196A1 PCT/CN2020/090867 CN2020090867W WO2021232196A1 WO 2021232196 A1 WO2021232196 A1 WO 2021232196A1 CN 2020090867 W CN2020090867 W CN 2020090867W WO 2021232196 A1 WO2021232196 A1 WO 2021232196A1
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laser
port
detector
circulator
optical fiber
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PCT/CN2020/090867
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French (fr)
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朱干军
关冉
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舍弗勒技术股份两合公司
朱干军
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Priority to PCT/CN2020/090867 priority Critical patent/WO2021232196A1/zh
Publication of WO2021232196A1 publication Critical patent/WO2021232196A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means

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  • the invention relates to the field of sensing and measurement, in particular to an optical fiber sensor and a method for position detection using the optical fiber sensor.
  • Fiber optic sensor is a device that can convert the physical parameters of the measured object into optical signals/photon signals. Its working principle is: the modulated laser is injected into the optical fiber, and the optical fiber is in physical contact with the area of interest. Since the laser signal propagating in the optical fiber will be affected by the environment of the area of interest, the interaction of photons and materials will affect the physical properties of the measured object. Parameters will be imprinted into the laser signal, resulting in changes in the laser signal's amplitude, modulation frequency, wavelength, pulse duration, and polarization state. By detecting the optical signal/photon signal output by the optical fiber, the physical parameters of the measured object can be obtained.
  • optical fiber sensors Compared with conventional sensors, optical fiber sensors have many advantages, such as high sensitivity, high accuracy, ruggedness, flexible implantation, and can be used to monitor a variety of physical parameters.
  • the optical fiber itself can not only serve as a sensor, but also as a signal transmission medium, thereby saving power, cables and signal channels.
  • Fiber optic sensors have shown strong capabilities as a new sensor technology and have been implemented in many application scenarios, such as security, construction machinery monitoring, power transmission, petroleum industry, aviation industry, medical measurement, scientific research, and more industries application.
  • optical fiber sensors do not have high requirements for the detection accuracy of specific locations where abnormal conditions occur. Therefore, currently existing optical fiber sensors cannot meet the ever-increasing requirements for location detection accuracy.
  • the technical problem to be solved by the present invention is to provide an optical fiber sensor with higher position detection accuracy to adapt to more and more application scenarios that require higher position detection accuracy.
  • an optical fiber sensor including: a laser generating device; a circulator having a first port, a second port, and a third port, wherein the first port is connected to the laser generating device A first detector, which is connected to the second port of the circulator; and a second detector, which is connected to the third port of the circulator.
  • the laser generating device generates measurement laser light, which is input from the first port to the circulator, and from the second port from the The circulator output; the first detector receives the forward scattered light generated by the measurement laser output from the second port after passing through the environment to be measured.
  • the backscattered light generated after the measurement laser output from the second port passes through the environment to be measured is input to the circulator from the second port, And output from the circulator from the third port; the second detector receives the backscattered light output from the third port.
  • optical fiber sensor in a possible implementation manner, it further includes: a control door, which is connected to both the first detector and the second port of the circulator, and is used to filter out the measurement The light other than the forward scattered light in the laser light.
  • optical fiber sensor in a possible implementation manner, it further includes: a processor, which is connected to both the first detector and the second detector, and receives the front detector according to the first detector.
  • the time of forward scattered light and the time of receiving the backscattered light by the second detector are used to determine the scattering of the measuring laser in the environment to be measured to generate the forward scattered light and the backscattered light. The position of the scattered light.
  • optical fiber sensor in a possible implementation manner, it further includes: a third detector, which is connected to both the laser generating device and the first port of the circulator, and is used to detect the measurement The time when the laser is input from the first port to the circulator, wherein the processor is also connected to the third detector, and the waiting time is determined according to the time detected by the third detector. A position in the measurement environment where the measurement laser is scattered to generate the forward scattered light and the backward scattered light.
  • the laser generating device includes: a laser generator, which generates laser light; and a laser pulse modulator, which is connected to the laser generator and modulates the laser light , To generate a laser pulse having a predetermined pulse width and a predetermined pulse interval; a pulse amplifier, which is connected to the laser pulse modulator, and amplifies the laser pulse to obtain the measurement laser.
  • a method for position detection using the above-mentioned optical fiber sensor which includes: using the laser generating device to generate measurement laser; Forward scattered light generated after measuring the environment; using the second detector to receive the backscattered light generated after the measuring laser passes through the environment to be measured; and receiving the forward scattered light according to the first detector
  • the time of scattered light and the time of receiving the backscattered light by the second detector are used to determine that the measurement laser is scattered in the environment to be measured to generate the forward scattered light and the backscattered light. The position of the scattered light.
  • the measurement laser generated by the laser generating device is input to the circulator from the first port, and output from the circulator from the second port;
  • the measurement laser output from the second port passes through the environment to be measured to generate the forward scattered light and the backward scattered light, wherein the forward scattered light is received by the second detector,
  • the backscattered light is input to the circulator from the second port, and output from the circulator to the second detector from the third port.
  • it further includes: using a control gate connected to both the first detector and the second port of the circulator to filter out the laser for measurement. Light other than the forward scattered light.
  • it further includes: using a third detector connected to both the laser generating device and the first port of the circulator to detect the laser for measurement.
  • the time when the first port is input to the circulator; and the time detected by the third detector is also used to determine the scattering of the measuring laser in the environment to be measured to generate the forward scattered light And the position of the backscattered light.
  • the first detector receives the forward scattered light generated after the measuring laser passes through the environment to be measured
  • the second detector receives the backscattered light generated after the measuring laser passes through the environment to be measured.
  • the optical fiber sensor and The method for position detection using the optical fiber sensor can accurately determine the use of the forward scattered light received by the first detector and the back scattered light received by the second detector. The position where the measurement laser light is scattered.
  • Fig. 1 shows a structural block diagram of an optical fiber sensor 100 according to an embodiment of the present invention
  • FIG. 2 shows a structural block diagram of an optical fiber sensor 200 according to another embodiment of the present invention
  • FIG. 3 shows a structural block diagram of an optical fiber sensor 300 according to another embodiment of the present invention.
  • FIG. 4 shows a schematic diagram of comparison between the position detection accuracy of the optical fiber sensor according to the embodiment of the present invention and the position detection accuracy of the optical fiber sensor of the comparative example;
  • Fig. 5 shows a flowchart of a method for position detection using an optical fiber sensor according to an embodiment of the present invention.
  • Fig. 1 shows a structural block diagram of an optical fiber sensor 100 according to an embodiment of the present invention.
  • the optical fiber sensor 100 mainly includes: a laser generating device 110, a circulator 120, a first detector 130 and a second detector 140.
  • the laser generating device 110 is used, for example, to generate a laser for measurement, and to inject the measurement laser into an optical fiber, and the optical fiber is in physical contact with the region of interest.
  • the circulator 120 has a first port A, a second port B, and a third port C, and the first port A is connected to the laser generating device 110.
  • the measurement laser is input to the circulator 120 from the first port A, and output from the circulator 120 from the second port B.
  • the optical fiber is coupled with the environment to be tested, once the environment to be tested changes, for example, the temperature, humidity, pH, etc. of the environment to be tested change, or the mechanical strength applied to the optical fiber changes, the optical fiber will be damaged.
  • the change of the physical structure affects its refractive index, causing the measurement laser light propagating in the optical fiber to be scattered, and scattered light propagating in all directions is generated.
  • scattered light can be emitted to different directions, it is often only allowed to propagate along the optical axis of the optical fiber, while suppressing propagation in other directions. Therefore, the optical fiber sensor 100 according to the present embodiment mainly uses the forward scattered light and the backward scattered light generated by the scattering of the measurement laser light.
  • the first detector 130 is connected to the second port B of the circulator 120. Therefore, in a possible implementation manner, the forward scattered light generated by the measurement laser output from the second port B after passing through the environment to be measured is received by the first detector 130. In addition, in a possible implementation manner, the backscattered light generated after the measurement laser output from the second port B passes through the environment to be measured is input from the second port B to the circulator 120, and from the third port C Output from the circulator 120.
  • the second detector 140 is connected to the third port C of the circulator 120, and therefore, the backscattered light output from the third port C is received by the second detector 140.
  • FIG. 1 is a structural block diagram of the optical fiber sensor 100 for the purpose of conveniently showing the manner in which the laser signal propagates.
  • the length of the optical fiber between the circulator 120 and the first detector 130 can reach 30km, or even 60km. above.
  • the optical fiber sensor 100 of the above-mentioned embodiment of the present invention can be based on the forward scattered light received by the first detector 130.
  • the light and the backscattered light received by the second detector 140 determine the position where the measurement laser is scattered in the environment to be measured.
  • both forward scattered light and backward scattered light are collected, that is to say, two recordings are performed for the same scattering event at the same time, which is the so-called coincidence recording. (coincidence recording), so it can greatly reduce the uncertainty of the distance of the scattering position, thereby improving the accuracy of position detection.
  • FIG. 2 shows a structural block diagram of an optical fiber sensor 200 according to another embodiment of the present invention.
  • the components with the same numbers in FIG. 2 as those in FIG. 1 have the same functions. For the sake of brevity, detailed descriptions of these components are omitted.
  • the optical fiber sensor 200 of this embodiment may further include a control door 150 on the basis of the optical fiber sensor 100 shown in FIG. 1.
  • the control gate 150 is connected to both the first detector 140 and the second port B of the circulator 120, and is used to filter out other light in the measurement laser except the forward scattered light, thereby improving The signal-to-noise ratio of the forward scattered light received by the first detector 130.
  • control gate 150 can be used to mainly filter out unscattered light pulses. Among them, due to the occurrence of scattering, there are differences in light frequency, arrival time, amplitude, etc. between scattered light and unscattered light. Therefore, the control gate 150 may be a grating for selecting light frequencies, or a timing gate for separating scattered light and unscattered light with different arrival times.
  • the unscattered light pulse (amplitude) can also be used together with the scattered light pulse to monitor the state of the region of interest, thereby describing all the information about the interaction between the photon and the material.
  • the optical fiber sensor 200 may further include a processor 160.
  • the processor 160 is connected to both the first detector 130 and the second detector 140, and is based on the time when the first detector 130 receives the forward scattered light and the second detector 140 receives the backscattered light. The time of light is used to determine the position where the measuring laser is scattered to generate the forward scattered light and the backward scattered light in the environment to be measured.
  • the travel time of the pulsed light before the scattering of the measurement laser is t0
  • the total propagation time T1 of the forward-scattered pulsed light signal can be detected by the first detector 130
  • the total propagation time T2 of the back-scattered pulsed light signal can be detected by the second detector 140.
  • the difference t1-t2 between the travel time of the forward scattered light and the travel time of the backscattered light after the occurrence of the scattering event can be detected by the first detector 130 and the arrival time of the forward scattered light and the first
  • the difference T1-T2 between the arrival times of the backscattered light detected by the two detectors 140 is obtained.
  • the position where the scattering occurs that is, the signal transcription point
  • the fiber length from the circulator 120 to the first detector 130 is S1
  • the fiber length from the circulator 120 to the second detector 140 is S2
  • the fiber from the circulator 120 to the position where the scattering occurs The length of the optical fiber is S11
  • the length of the optical fiber from the scattering position to the first detector 130 is S12.
  • S11+S12 S1
  • v ⁇ t1 S12
  • v ⁇ t2 S11+S2.
  • v is the propagation speed of light in the optical fiber.
  • the optical fiber sensor 200 may further include: a third detector 170.
  • the third detector 170 is connected to both the laser generating device 110 and the first port A of the circulator 120, and is used to detect the time when the measuring laser is input to the circulator from the first port.
  • the processor 160 is also connected to the third detector 170, and also determines according to the time detected by the third detector 170 that the measurement laser is scattered in the environment to be measured to generate the The positions of the forward scattered light and the backward scattered light.
  • the third detector 170 can play a role of "notifying that the measurement laser has been emitted.” That is, the processor 160 is notified of the start of measurement. As a result, it is possible to more accurately determine the time when the forward scattered light and the backward scattered light generated for the same laser pulse reach the first detector and the second detector, respectively, thereby further improving the scattering of the measurement laser light. The position detection accuracy of the position.
  • the principle of coincidence recording can also be used to accurately determine the measurement.
  • the location where the laser light is scattered. Therefore, the optical fiber sensor 200 according to this embodiment may also not require the absolute time of laser pulse emission.
  • the third detector 170 may not be required as a trigger for the measurement start. Therefore, the third detector 170 may be omitted.
  • FIG. 3 shows a structural block diagram of an optical fiber sensor 300 according to another embodiment of the present invention.
  • the components in FIG. 3 with the same numbers as those in FIG. 1 and FIG. 2 have the same functions. For the sake of brevity, detailed descriptions of these components are omitted.
  • the laser generating device 110 may include: a laser generator 111, a laser pulse Modulator 112 and pulse amplifier 113.
  • the laser generator 111 generates laser light
  • the laser pulse modulator 112 is connected to the laser generator 111, and modulates the laser light to generate laser pulses having a predetermined pulse width and a predetermined pulse interval
  • the pulse amplifier 113 modulates the laser pulse
  • the device 112 is connected, and amplifies the laser pulse to obtain the measurement laser. Amplifying the laser pulse by the pulse amplifier 113 can help transmit the laser pulse for a long distance.
  • the modulation controller 114 may be used to control the laser pulse modulator 112 so that the laser pulse modulator 112 can generate laser pulses with a predetermined pulse width, for example, 100 ns and a predetermined pulse interval, for example, 150 ns.
  • a predetermined pulse width for example, 100 ns
  • a predetermined pulse interval for example, 150 ns.
  • the specific pulse width and pulse interval to be used can be determined by those skilled in the art according to actual application scenarios, and the present invention is not limited.
  • the above-mentioned laser generator 111, laser pulse modulator 112, and pulse amplifier 113 may be separate devices, or may be integrated in an optical fiber.
  • the present invention also does not limit this.
  • the optical fiber sensor 300 according to this embodiment can achieve the same technical effects as the optical fiber sensor 100 shown in FIG. 1 and the optical fiber sensor 200 shown in FIG. 2, which will not be repeated here.
  • ⁇ Z is the spatial (distance) resolution
  • c is the propagation speed of light in vacuum
  • T is the duration of the modulated pulse
  • n is the refractive index of the optical fiber.
  • the only way to improve the spatial (distance) resolution of the fiber optic sensor is to reduce the duration of the modulated laser pulse. However, this will reduce the intensity of the laser pulse, resulting in maximizing the length of the fiber optic sensor. In addition, the shorter the laser pulse duration, the more expensive laser pulse modulators and electronic switch controllers are needed.
  • the present invention proposes an alternative scheme to record pulses transcribed with scattered information.
  • the present invention in accordance with the principle of recording, in addition to recording the backward scattered light pulse, the forward scattered light pulse is also recorded. Therefore, the present invention can more accurately determine the position where the measurement laser is scattered in the environment to be measured.
  • the duration of the laser pulse used is the same, the present invention has higher position detection accuracy than the above-mentioned optical fiber sensor.
  • Fig. 5 shows a flowchart of a method for position detection using an optical fiber sensor according to an embodiment of the present invention.
  • the method mainly includes the following steps:
  • Step S400 using the laser generating device to generate a laser for measurement
  • Step S401 using the first detector to receive forward scattered light generated by the measuring laser after passing through the environment to be measured;
  • Step S402 using the second detector to receive the backscattered light generated by the measuring laser after passing through the environment to be measured;
  • Step S403 according to the time when the first detector receives the forward scattered light and the time when the second detector receives the backscattered light, it is determined that the measurement laser is used in the environment to be measured. The position where scattering occurs to generate the forward scattered light and the backward scattered light.
  • the measurement laser generated by the laser generating device is input to the circulator from the first port, and output from the circulator from the second port;
  • the measurement laser output from the second port passes through the environment to be measured to generate the forward scattered light and the backward scattered light, wherein the forward scattered light is received by the second detector,
  • the backscattered light is input to the circulator from the second port, and output from the circulator to the second detector from the third port.
  • it further includes: using a control gate connected to both the first detector and the second port of the circulator to filter out the laser for measurement. Light other than the forward scattered light.
  • it further includes: using a third detector connected to both the laser generating device and the first port of the circulator to detect the laser for measurement.
  • the time when the first port is input to the circulator; and the time detected by the third detector is also used to determine the scattering of the measuring laser in the environment to be measured to generate the forward scattered light And the position of the backscattered light.
  • the first detector receives the forward scattered light generated after the measurement laser passes through the environment to be measured
  • the second detector receives the backscattered light generated after the measurement laser passes through the environment to be measured.
  • the present invention proposes The method of using the optical fiber sensor for position detection can accurately determine the location in the environment to be measured based on the forward scattered light received by the first detector and the back scattered light received by the second detector. The position where the laser light for measurement is scattered. Therefore, according to the method for position detection using the optical fiber sensor proposed in the present invention, the distance uncertainty of the scattering position can be greatly reduced, thereby improving the position detection accuracy.

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Abstract

一种光纤传感器（100）以及利用光纤传感器（100）进行位置检测的方法。光纤传感器（100）包括：激光生成装置（110）；环形器（120），其具有第一端口（A）、第二端口（B）和第三端口（C），其中，第一端口（A）与激光生成装置（110）连接；第一检测器（130），其与环形器（120）的第二端口（B）连接；以及第二检测器（140），其与环形器（120）的第三端口（C）连接。通过第一检测器（130）接收测量用激光经过待测环境之后而生成的前向散射光，第二检测器（140）接收测量用激光经过待测环境之后而生成的后向散射光。光纤传感器（100）以及利用光纤传感器（100）进行位置检测的方法能够根据第一检测器（130）接收到的前向散射光和第二检测器（140）接收到的后向散射光，来精确地确定待测环境中使测量用激光发生散射的位置。

Description

光纤传感器以及利用该光纤传感器进行位置检测的方法 技术领域
本发明涉及一种传感测量领域，尤其涉及一种光纤传感器以及利用该光纤传感器进行位置检测的方法。
背景技术
光纤传感器是一种可以将被测对象的物理参数转换为光信号/光子信号的设备。其工作原理是：使调制后的激光注入光纤，光纤与关注区域物理接触，由于光纤内传播的激光信号会受到关注区域环境的影响，因此在光子和材料的相互作用下，被测对象的物理参数将被转录(imprinted)到该激光信号中，导致该激光信号的例如振幅、调制频率、波长、脉冲持续时间和偏振状态等发生改变。通过检测光纤所输出的光信号/光子信号，可以得出被测对象的物理参数。
光纤传感器相比常规传感器具有很多优点，例如灵敏度高、精度高、坚固耐用、植入灵活、可用于多种物理参数监测等。另外，光纤本身不仅可以充当传感器，还可以充当信号传输的媒介，从而节省了电源、线缆和信号通道。
光纤传感器作为新型传感器技术显示出强大的能力，并且已经在许多应用场景中得以实施，例如安全保障、建筑机械监控、电力传输、石油工业、航空工业、医学测量、科学研究以及其它更多的工业应用。
然而，目前光纤传感器的应用场景对出现异常情况的具***置的检测精度要求不高，因此目前存在的光纤传感器不能满足日益增长的对位置检测精度的要求。
发明内容
技术问题
有鉴于此，本发明要解决的技术问题是，提供一种具有较高位置检测精度的光纤传感器，以适应越来越多的对位置检测精度要求较高的应用场景。
解决方案
根据本发明的一个方面，提供一种光纤传感器，包括：激光生成装置；环形器，其具有第一端口、第二端口和第三端口，其中，所述第一端口与所述激光生成装置连接；第一检测器，其与所述环形器的所述第二端口连接；以及第二检测器，其与所述环形器的所述第三端口连接。
对于上述光纤传感器，在一种可能的实现方式中，所述激光生成装置生成测量用激光，所述测量用激光自所述第一端口输入至所述环形器，并自所述第二端口从所述环形器输出；所述第一检测器接收自所述第二端口输出的测量用激光经过待测环境之后而生成的前向散射光。
对于上述光纤传感器，在一种可能的实现方式中，自所述第二端口输出的测量用激光经过待测环境之后而生成的后向散射光自所述第二端口输入至所述环形器，并自所述第三端口从所述环形器输出；所述第二检测器接收自所述第三端口输出的所述后向散射光。
对于上述光纤传感器，在一种可能的实现方式中，还包括：控制门，其与所述第一检测器和所述环形器的所述第二端口均连接，用于滤除所述测量用激光中除所述前向散射光之外的其它光。
对于上述光纤传感器，在一种可能的实现方式中，还包括：处理器，其与所述第一检测器和所述第二检测器均连接，并根据所述第一检测器接收所述前向散射光的时间和所述第二检测器接收所述后向散射光的时间，来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
对于上述光纤传感器，在一种可能的实现方式中，还包括：第三检测器，其与所述激光生成装置和所述环形器的所述第一端口均连接，用于检测所述测量用激光自所述第一端口输入至所述环形器的时间，其中，所述处理器还与所述第三检测器连接，并且还根据所述第三检测器所检测的时间来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
对于上述光纤传感器，在一种可能的实现方式中，所述激光生成装置包括：激光发生器，其生成激光；激光脉冲调制器，其与所述激光发生器连接，并对所述激光进行调制，以生成具有预定脉冲宽度和预定脉冲间隔的激光脉冲；脉冲放大器，其与所述激光脉冲调制器连接，并对所述激光脉冲进行放 大从而得到所述测量用激光。
根据本发明的另一方面，提供一种利用上述的光纤传感器进行位置检测的方法，包括：利用所述激光生成装置生成测量用激光；利用所述第一检测器接收所述测量用激光经过待测环境之后而生成的前向散射光；利用所述第二检测器接收所述测量用激光经过待测环境之后而生成的后向散射光；以及根据所述第一检测器接收所述前向散射光的时间和所述第二检测器接收所述后向散射光的时间，来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
对于上述方法，在一种可能的实现方式中，所述激光生成装置生成的测量用激光自所述第一端口输入至所述环形器，并自所述第二端口从所述环形器输出；自所述第二端口输出的测量用激光经过待测环境之后而生成所述前向散射光和所述后向散射光，其中，所述前向散射光被所述第二检测器所接收，所述后向散射光自所述第二端口输入至所述环形器，并自所述第三端口从所述环形器输出至所述第二检测器。
对于上述方法，在一种可能的实现方式中，还包括：利用与所述第一检测器和所述环形器的所述第二端口均连接的控制门，滤除所述测量用激光中除所述前向散射光之外的其它光。
对于上述方法，在一种可能的实现方式中，还包括：利用与所述激光生成装置和所述环形器的所述第一端口均连接的第三检测器，检测所述测量用激光自所述第一端口输入至所述环形器的时间；以及还根据所述第三检测器所检测的时间来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
有益效果
通过第一检测器接收测量用激光经过待测环境之后而生成的前向散射光，第二检测器接收测量用激光经过待测环境之后而生成的后向散射光，本发明提出的光纤传感器和利用该光纤传感器进行位置检测的方法能够根据第一检测器接收到的所述前向散射光和第二检测器接收到的所述后向散射光，来精确地确定所述待测环境中使所述测量用激光发生散射的位置。
根据下面参考附图对示例性实施例的详细说明，本发明的其它特征及方面将变得清楚。
附图说明
包含在说明书中并且构成说明书的一部分的附图与说明书一起示出了本发明的示例性实施例、特征和方面，并且用于解释本发明的原理。
图1示出根据本发明一实施例的光纤传感器100的结构框图；
图2示出根据本发明另一实施例的光纤传感器200的结构框图；
图3示出根据本发明又一实施例的光纤传感器300的结构框图；
图4示出根据本发明实施例的光纤传感器的位置检测精度与比较例的光纤传感器的位置检测精度之间的对比示意图；
图5示出根据本发明一实施例的利用光纤传感器进行位置检测的方法的流程图。
具体实施方式
以下将参考附图详细说明本发明的各种示例性实施例、特征和方面。附图中相同的附图标记表示功能相同或相似的元件。尽管在附图中示出了实施例的各种方面，但是除非特别指出，不必按比例绘制附图。
在这里专用的词“示例性”意为“用作例子、实施例或说明性”。这里作为“示例性”所说明的任何实施例不必解释为优于或好于其它实施例。
另外，为了更好的说明本发明，在下文的具体实施方式中给出了众多的具体细节。本领域技术人员应当理解，没有某些具体细节，本发明同样可以实施。在另外一些实例中，对于本领域技术人员熟知的方法、手段、元件和电路未作详细描述，以便于凸显本发明的主旨。
实施例1
图1示出根据本发明一实施例的光纤传感器100的结构框图。如图1所示，该光纤传感器100主要包括：激光生成装置110、环形器120、第一检测器130和第二检测器140。其中，激光生成装置110例如用于生成测量用激光，并使得该测量激光注入光纤，光纤与关注区域物理接触。环形器120具有第一端口A、第二端口B和第三端口C，第一端口A与激光生成装置110连接。在一种可能的实现方式中，所述测量用激光自第一端口A输入至环形器120，并自第二端口B从环形器120输出。
由于所述光纤与待测环境耦合，因此一旦该待测环境发生变化，例如该待测环境的温度、湿度、酸碱度等发生变化，或者施加到该光纤上的机械强度发生变化，将使得光纤的物理结构发生变化进而影响其折射率，导致在该光纤内传播的所述测量用激光发生散射，而生成向各个方向传播的散射光。尽管散射光可以发射到不同的方向，但是往往仅允许光沿着光纤的光轴传播，而抑制向其余方向的传播。因此，根据本实施例的光纤传感器100主要利用了所述测量用激光发生散射而生成的前向散射光和后向散射光。
此外，第一检测器130与环形器120的第二端口B连接。由此，在一种可能的实现方式中，自第二端口B输出的测量用激光经过待测环境之后而生成的前向散射光被该第一检测器130所接收。另外，在一种可能的实现方式中，自第二端口B输出的测量用激光经过待测环境之后而生成的后向散射光自第二端口B输入至环形器120，并自第三端口C从环形器120输出。第二检测器140与环形器120的第三端口C连接，因此，自第三端口C输出的所述后向散射光被该第二检测器140所接收。
需要说明的是，在图1中，箭头示意性示出了激光信号的传播方向，实线示意性示出了测量用激光的传播路径，虚线示意性示出了后向散射光的传播路径，点划线示意性示出了前向散射光的传播路径。并且，图1是以方便示出激光信号传播的方式为目的，而示出的光纤传感器100的结构框图。实际上，虽然可以将环形器120和第一检测器130之间在物理上的实际距离设置为非常接近，但是自环形器120到第一检测器130之间的光纤长度可达到30km，甚至60km以上。
这样，由于测量用激光发生散射而生成的向各个方向传播的散射光可以携带光材料的信息，因此本发明上述实施例的光纤传感器100能够根据第一检测器130接收到的所述前向散射光和第二检测器140接收到的所述后向散射光来确定所述待测环境中使所述测量用激光发生散射的位置。并且，由于在本发明上述实施例的光纤传感器100中，既收集了前向散射光又收集了后向散射光，也就说针对同一散射事件同时进行了两次记录、也即所谓的符合记录(coincidence recording)，因此可以大大减少发生散射位置的距离不确定性，从而提高了位置检测精度。
实施例2
图2示出根据本发明另一实施例的光纤传感器200的结构框图。图2中标号与图1相同的组件具有相同的功能，为简明起见，省略对这些组件的详细说明。
如图2所示，本实施例的光纤传感器200在图1所示的光纤传感器100基础上，还可以包括：控制门150。其中，控制门150与第一检测器140和环形器120的第二端口B均连接，用于滤除所述测量用激光中除所述前向散射光之外的其它光，由此能够提高被该第一检测器130所接收的所述前向散射光的信噪比。
在一种可能的实现方式中，控制门150可以用于主要滤除未散射的光脉冲。其中，由于发生了散射，因此散射光和未发生散射的光之间在光频率、到达时间、振幅等方面存在差异。因此，该控制门150可以是用于选择光频率的光栅，也可以是用于将到达时间不同的散射光和未散射的光分开的定时门。
另外，未散射的光脉冲(振幅)也可以与散射后的光脉冲一起用于关注区域的状态监视，由此可以描述光子与材料之间的相互作用的全部信息。
在一种可能的实现方式中，如图2所示，根据本实施例的光纤传感器200还可以包括：处理器160。其中，处理器160与第一检测器130和第二检测器140均连接，并根据第一检测器130接收到所述前向散射光的时间和第二检测器140接收到所述后向散射光的时间，来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
在这种实现方式中，假设测量用激光发生散射之前的脉冲光的行进时间为t0，发生散射之后的前向散射脉冲光和后向散射脉冲光的行进时间分别为的t1和t2。因此，前向散射脉冲光信号的总传播时间T1＝t0+t1，后向散射脉冲光信号的总传播时间T2＝t0+t2。由此可以得出，T1-T2＝t1-t2。其中，前向散射脉冲光信号的总传播时间T1可以通过第一检测器130检测得到，后向散射脉冲光信号的总传播时间T2可以通过第二检测器140检测得到。因此，在发生了散射事件之后前向散射光的行进时间和后向散射光的行进时间之间的差t1-t2，可以通过第一检测器130检测得到的前向散射光的到达时间和第二检测器140检测得到的后向散射光的到达时间之间的差T1-T2得出。这样，在给定光路(主要是光纤)的总长度的情况下，可以通过时间差精确地得出 发生散射的位置(也就是信号转录点)。
举例而言，假设自环形器120到第一检测器130之间的光纤长度为S1，自环形器120到第二检测器140之间的光纤长度为S2，自环形器120到发生散射的位置的光纤长度为S11，自发生散射的位置到第一检测器130之间的光纤长度为S12，则存在如下公式：S11+S12＝S1；v×t1＝S12；v×t2＝S11+S2。其中，v是光在光纤中的传播速度。结合上述公式，可以得到自环形器120到发生散射的位置的光纤长度S11，也就确定了待测环境中发生散射的具***置。
在一种可能的实现方式中，如图2所示，根据本实施例的光纤传感器200还可以包括：第三检测器170。其中，该第三检测器170与激光生成装置110和环形器120的第一端口A均连接，用于检测所述测量用激光自所述第一端口输入至所述环形器的时间。在这种实现方式中，处理器160还与第三检测器170连接，并且还根据第三检测器170所检测的时间来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
这样，第三检测器170能够起到“通知测量用激光已发出”的作用。也就是说，向处理器160通知测量开始。由此，能够更精确地确定针对同一激光脉冲生成的前向散射光和后向散射光分别到达第一检测器和第二检测器的时间，从而进一步提高了对使所述测量用激光发生散射的位置的位置检测精度。
当然，如上所述，仅根据在发生了散射事件之后前向散射光的行进时间和后向散射光的行进时间之间的差t1-t2，利用符合记录原理也能够精确地确定使所述测量用激光发生散射的位置。因此，根据本实施例的光纤传感器200也可以不需要激光脉冲发出的绝对时间。也就是说，可以不需要第三检测器170作为测量开始的触发。因此，第三检测器170可以省略。
实施例3
图3示出根据本发明又一实施例的光纤传感器300的结构框图。图3中标号与图1和图2相同的组件具有相同的功能，为简明起见，省略对这些组件的详细说明。
如图3所示，在本实施例的光纤传感器300中，对于图1所示的光纤传感器100和图2所示的光纤传感器200，其激光生成装置110可以包括：激光发生 器111、激光脉冲调制器112和脉冲放大器113。其中，激光发生器111生成激光，激光脉冲调制器112与激光发生器111连接，并对所述激光进行调制，以生成具有预定脉冲宽度和预定脉冲间隔的激光脉冲，脉冲放大器113与激光脉冲调制器112连接，并对所述激光脉冲进行放大从而得到所述测量用激光。通过脉冲放大器113对所述激光脉冲进行放大，能够帮助将激光脉冲传输很长的距离。
另外，如图3所示，可以使用调制控制器114来对激光脉冲调制器112进行控制，以使得该激光脉冲调制器112能够生成预定脉冲宽度例如100ns和预定脉冲间隔例如150ns的激光脉冲。当然，具体采用何种脉冲宽度和脉冲间隔，本领域技术人员完全可以根据实际应用场景来决定，本发明不做限定。
在一种可能的实现方式中，上述的激光发生器111、激光脉冲调制器112和脉冲放大器113可以是单独的器件，也可以集成在光纤中。本发明对此也不做限定。
根据本实施例的光纤传感器300能够实现与图1所示的光纤传感器100和图2所示的光纤传感器200相同的技术效果，这里不再赘述。
下面结合一个比较例来说明本发明提出的光纤传感器所具有的优异效果。
目前存在一种光纤传感器的标准方案，其利用激光脉冲调制器生成激光脉冲，并且使得所生成的激光脉冲注入入传感器光纤进行传播，利用一个检测器记录激光脉冲进入光纤的“发出时间”。在该激光脉冲受到待测环境的影响而发生散射的情况下，转录有散射信息的脉冲将被发送到另一检测器，并由该检测器记录接收到该压印有散射信息的脉冲的时间。由于后向散射光相比前向散射光具有更好的信噪比，因此现有的光纤传感器通常仅检测后向散射光，并由此确定使所述激光脉冲发生散射的位置。
在上述的光纤传感器的检测方案中，空间(距离)分辨率受激光脉冲的持续时间的限制，如下式所示：ΔZ＝c×T/2n。其中，ΔZ是空间(距离)分辨率，c是光在真空中的传播速度，T是调制脉冲的持续时间，n是光纤的折射率。
因此，提高该光纤传感器的空间(距离)分辨率的唯一方法是减少调制后的激光脉冲的持续时间。然而，这将减小激光脉冲的强度，从而导致光 纤传感器的长度最大化。此外，越短的激光脉冲持续时间，越需要更昂贵的激光脉冲调制器和电子开关控制器。
如在实施例1～3中所述，本发明提出了一种替代方案来记录转录有散射信息的脉冲。其中，在本发明中，利用符合记录原理，除了记录后向散射光脉冲之外，还记录了前向散射光脉冲。因此，本发明能够更精确地确定所述待测环境中使所述测量用激光发生散射的位置。在所使用的激光脉冲的持续时间相同的情况下，本发明相比上述的光纤传感器具有较高的位置检测精度。
如上所述，在作为比较例的上述现有的光纤传感器中，其信号收集方法仅使用后向散射光，空间分辨率取决于激光脉冲的持续时间。因此，如图4所示，存在发生散射位置的距离不确定性。而在本发明提出的光纤传感器中，既收集了后向散射光又收集了前向散射光，通过符合记录原理即针对同一散射事件同时进行记录，可以大大减少发生散射位置的距离不确定性。
实施例4
图5示出根据本发明一实施例的利用光纤传感器进行位置检测的方法的流程图。
如图5所示，该方法主要包括以下步骤：
步骤S400、利用所述激光生成装置生成测量用激光；
步骤S401、利用所述第一检测器接收所述测量用激光经过待测环境之后而生成的前向散射光；
步骤S402、利用所述第二检测器接收所述测量用激光经过待测环境之后而生成的后向散射光；以及
步骤S403、根据所述第一检测器接收所述前向散射光的时间和所述第二检测器接收所述后向散射光的时间，来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
对于上述方法，在一种可能的实现方式中，所述激光生成装置生成的测量用激光自所述第一端口输入至所述环形器，并自所述第二端口从所述环形器输出；自所述第二端口输出的测量用激光经过待测环境之后而生成所述前向散射光和所述后向散射光，其中，所述前向散射光被所述第二检测器所接收，所述后向散射光自所述第二端口输入至所述环形器，并自所述第三端 口从所述环形器输出至所述第二检测器。
对于上述方法，在一种可能的实现方式中，还包括：利用与所述第一检测器和所述环形器的所述第二端口均连接的控制门，滤除所述测量用激光中除所述前向散射光之外的其它光。
对于上述方法，在一种可能的实现方式中，还包括：利用与所述激光生成装置和所述环形器的所述第一端口均连接的第三检测器，检测所述测量用激光自所述第一端口输入至所述环形器的时间；以及还根据所述第三检测器所检测的时间来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
关于上述的光纤传感器、激光生成装置、第一检测器、第二检测器、第三检测器、环形器、控制门、第一端口、第二端口以及第三端口等的结构、功能及相应的连接关系，在上述实施例1～3中已经进行了详细说明，这里不再重复描述。
由此，通过第一检测器接收测量用激光经过待测环境之后而生成的前向散射光，第二检测器接收测量用激光经过待测环境之后而生成的后向散射光，本发明提出的利用光纤传感器进行位置检测的方法能够根据第一检测器接收到的所述前向散射光和第二检测器接收到的所述后向散射光，来精确地确定所述待测环境中使所述测量用激光发生散射的位置。因此，根据本发明提出的利用光纤传感器进行位置检测的方法，可以大大减少发生散射位置的距离不确定性，从而提高了位置检测精度。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (11)

  1. 一种光纤传感器，其特征在于，包括：
    激光生成装置；
    环形器，其具有第一端口、第二端口和第三端口，其中，所述第一端口与所述激光生成装置连接；
    第一检测器，其与所述环形器的所述第二端口连接；以及
    第二检测器，其与所述环形器的所述第三端口连接。
  2. 根据权利要求1所述的光纤传感器，其特征在于，
    所述激光生成装置生成测量用激光，所述测量用激光自所述第一端口输入至所述环形器，并自所述第二端口从所述环形器输出；
    所述第一检测器接收自所述第二端口输出的测量用激光经过待测环境之后而生成的前向散射光。
  3. 根据权利要求2所述的光纤传感器，其特征在于，
    自所述第二端口输出的测量用激光经过待测环境之后而生成的后向散射光自所述第二端口输入至所述环形器，并自所述第三端口从所述环形器输出；
    所述第二检测器接收自所述第三端口输出的所述后向散射光。
  4. 根据权利要求2所述的光纤传感器，其特征在于，还包括：
    控制门，其与所述第一检测器和所述环形器的所述第二端口均连接，用于滤除所述测量用激光中除所述前向散射光之外的其它光。
  5. 根据权利要求3所述的光纤传感器，其特征在于，还包括：
    处理器，其与所述第一检测器和所述第二检测器均连接，并根据所述第一检测器接收所述前向散射光的时间和所述第二检测器接收所述后向散射光的时间，来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
  6. 根据权利要求5所述的光纤传感器，其特征在于，还包括：
    第三检测器，其与所述激光生成装置和所述环形器的所述第一端口均连接，用于检测所述测量用激光自所述第一端口输入至所述环形器的时间，其中，所述处理器还与所述第三检测器连接，并且还根据所述第三检测器所检测的时间来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
  7. 根据权利要求2所述的光纤传感器，其特征在于，所述激光生成装置包括：
    激光发生器，其生成激光；
    激光脉冲调制器，其与所述激光发生器连接，并对所述激光进行调制，以生成具有预定脉冲宽度和预定脉冲间隔的激光脉冲；
    脉冲放大器，其与所述激光脉冲调制器连接，并对所述激光脉冲进行放大从而得到所述测量用激光。
  8. 一种利用权利要求1所述的光纤传感器进行位置检测的方法，其特征在于，包括：
    利用所述激光生成装置生成测量用激光；
    利用所述第一检测器接收所述测量用激光经过待测环境之后而生成的前向散射光；
    利用所述第二检测器接收所述测量用激光经过待测环境之后而生成的后向散射光；以及
    根据所述第一检测器接收所述前向散射光的时间和所述第二检测器接收所述后向散射光的时间，来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
  9. 根据权利要求8所述的方法，其特征在于，
    所述激光生成装置生成的测量用激光自所述第一端口输入至所述环形器，并自所述第二端口从所述环形器输出；
    自所述第二端口输出的测量用激光经过待测环境之后而生成所述前向散射光和所述后向散射光，其中，所述前向散射光被所述第二检测器所接收，所述后向散射光自所述第二端口输入至所述环形器，并自所述第三端口从所述环形器输出至所述第二检测器。
  10. 根据权利要求8所述的方法，其特征在于，还包括：
    利用与所述第一检测器和所述环形器的所述第二端口均连接的控制门，滤除所述测量用激光中除所述前向散射光之外的其它光。
  11. 根据权利要求8至10中任一项所述的方法，其特征在于，还包括：
    利用与所述激光生成装置和所述环形器的所述第一端口均连接的第三检测器，检测所述测量用激光自所述第一端口输入至所述环形器的时间；以 及
    还根据所述第三检测器所检测的时间来确定所述待测环境中使所述测量用激光发生散射而生成所述前向散射光和所述后向散射光的位置。
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