A kind of Polarization-Sensitive distributed perturbation sensing measuring method and system
Technical field
The present invention relates to a kind of optical fiber sensing system, relate in particular to a kind of Polarization-Sensitive distributed perturbation method for sensing and system based on polarization beam apparatus and balance amplification photoelectric commutator.
Background technology
Extraneous extruding, impact, vibration etc. all can cause the disturbance of optical fiber, and these perturbation meetings cause the variation of fiber birefringence axle and then cause the variation of the light signal polarization state of transmitting in the optical fiber.Utilize above-described polarization state variation characteristic just based on the moving optical fiber sensing system of Polarization-Sensitive distributed perturbation, come perception optical fiber whether to be subjected to external interference along the line by the polarization state of analyzing the Rayleigh scattering light signal that transmits dorsad in the optical fiber.
In the prior art, the measuring method of light signal polarization state has multiple, comprise analyzing meter method and based on the method for polarization beam apparatus and double detector, analyzing meter method is the variation of reacting polarization state through the light signal strength of analyzing meter by measuring, and the method can not make full use of the energy of tested light signal; Method based on polarization beam apparatus and double detector is to use polarization beam apparatus that tested light signal is divided into orthogonal two ways of optical signals, two ways of optical signals with polarization beam apparatus output is input to two photodetectors respectively then, gather the data of two paths of signals then respectively and do data processing respectively, though the method can make full use of the energy of light signal but need use two photodetectors because of system, structure is complicated, and data volume is big, the data processing time that needs is longer, causes the response time of system longer.Find after deliberation in addition after carrying out spectrum transformation, to cause the reason of measuring blind spot not to be because polarized light signal is zero with vertical this road light signal output intensity that causes of a polarization axle wherein based on Polarization-Sensitive distributed perturbation sensor, but because the polarization state that causes by perturbation change with change before compare very faintly, the method that therefore how to provide a kind of highly sensitive measurement polarization state to change is to optimize the problem that need solve based on Polarization-Sensitive distributed perturbation sensor-based system.
Summary of the invention
The purpose of this invention is to provide the method that a kind of highly sensitive measurement polarization state changes, and based on this method proposition a kind of Polarization-Sensitive distributed perturbation sensing measuring method and system, to overcome the deficiency of prior art scheme based on polarization beam apparatus and balance amplification photoelectric commutator.
Above-mentioned measuring method of amplifying the Polarization-Sensitive distributed perturbation optical fiber sensing system of photoelectric commutator based on polarization beam apparatus and balance of the present invention is meant the method that polarization state changes of measuring, technical scheme of the present invention is: a kind of Polarization-Sensitive distributed perturbation method for sensing, to in the sensor fibre or react optical fiber by a circulator to the polarization state measurement of the light signal of Rayleigh scattering dorsad that detectable signal produced of sensor fibre and whether be subjected to external interference along the line, at first use a polarization beam apparatus to be divided into mutually orthogonal two-way polarized light in the sensor fibre or through the tested rayleigh backscattering light signal of circulator output, then this two-way polarized light signal is imported balance respectively and amplified two input ports of photoelectric commutator, the polarization state that draws two ways of optical signals changes the poor of the light intensity that causes.Balance is amplified the output of photoelectric commutator (being the difference photo amplifier), and the polarization state that draws two ways of optical signals changes the poor of the light intensity that causes.
Device of the present invention is achieved through the following technical solutions: based on the Polarization-Sensitive distributed perturbation optical fiber sensing system of polarization beam apparatus and balance amplification photoelectric commutator, comprise: function generator 1, pulsed laser 2, Polarization Controller 3, circulator 4, sensor fibre 5, polarization beam apparatus 6, balance is amplified photoelectric commutator 7, data acquisition unit 8, data processing unit 9; Two synchronous triggering output ports of described function generator 1 connect respectively and trigger the input end of described pulsed laser 2 and the triggering input port of described data acquisition unit 8; The output terminal of described pulsed laser 2 connects the input end of described Polarization Controller 3; The output terminal of described Polarization Controller 3 connects described circulator 4 ports
The port of described circulator 4
Connect described sensor fibre 5; Described circulator 4 ports
The input end that connects described polarization beam apparatus 6; Two output ports of described polarization beam apparatus 6 connect two input ports that balance is amplified photoelectric commutator 7; Described balance is amplified the data acquisition input port of the output port connection data acquisition unit 8 of photoelectric commutator 7; The output terminal of described data acquisition unit 8 connects the input end of data processing unit 9.
The above-mentioned tested rayleigh backscattering flashlight of sensor fibre (or passing through circulator) being exported based on the photoelectric commutator of balance amplification described in the Polarization-Sensitive distributed perturbation optical fiber sensing system of polarization beam apparatus and amplification photoelectric commutator (balance photodetector) of the present invention subtracts each other through the intensity of the two-way polarized light signal of polarization beam apparatus (PBS) beam splitting gained, and the energy difference that makes full use of the polarization signal of two-way energy complement reacts the polarization state variation that extraneous perturbation brings.
As seen from the above technical solution provided by the invention, of the present invention based on the Polarization-Sensitive distributed perturbation sensor-based system of polarization beam apparatus and balance amplification photoelectric commutator and the method that the measurement polarization state changes thereof, the polarization state of using balance amplification photoelectric commutator that the intensity of two-way quadrature input optical signal is subtracted each other and obtaining changes the intensity difference that causes, utilizes data processing unit that the signal that is obtained by data acquisition is carried out analyzing and processing again.Can realize Sensitive Detection to optical fiber perturbation signal.
The invention has the beneficial effects as follows: propose the method that a kind of highly sensitive measurement polarization state changes, and based on a kind of Polarization-Sensitive distributed perturbation sensing measurement system of this method proposition based on polarization beam apparatus and balance amplification photoelectric commutator, overcome the deficiency of prior art scheme, with compare based on the method for polarization beam apparatus and double detector, the present invention has simplified system and has saved cost; Compare with analyzing meter method, the present invention can improve 3dB with the measurable dynamic range of system, the detectable minimum energy of system can have been improved 3dB again simultaneously.
Description of drawings
Fig. 1 is an analyzing meter method schematic diagram of measuring polarization state in the prior art
Fig. 2 is the method schematic diagram based on polarization beam apparatus and double detector of measuring polarization state in the prior art
Fig. 3 is the method block diagram based on polarization beam apparatus and balance amplification photoelectric commutator of the measurement polarization state among the present invention
Fig. 4 is the structured flowchart of the optical fiber perturbation sensor-based system among the present invention.
Embodiment
Describe preferred embodiment of the present invention in detail below in conjunction with accompanying drawing.
Polarization-Sensitive distributed perturbation optical fiber sensing system based on polarization beam apparatus and balance amplification photoelectric commutator of the present invention, its preferable embodiment as shown in Figure 4, comprise function generator 1, pulsed laser 2, Polarization Controller 3, circulator 4, sensor fibre 5, polarization beam apparatus 6, balance is amplified photoelectric commutator 7, data acquisition unit 8, data processing unit 9.
Concrete implementation step when the present invention is used to monitor is as follows:
1) described function generator 1 sends two synchronous triggering signals and is respectively applied for described pulsed laser 2 of triggering and described data acquisition unit 8.
2) the direct impulse light signal of described pulsed laser 2 outputs passes through described Polarization Controller 3, described circulator 4
,
Port enters described sensor fibre 5.
3) light of Rayleigh scattering signal dorsad that produces in described sensor fibre 5 of described direct impulse light is through described circulator 4
,
Port enters described polarization beam apparatus 6.
4) described polarization beam apparatus 6 is with after Rayleigh scattering signal light is divided into orthogonal two polarization modes dorsad, and two output ports through described polarization beam apparatus 6 enter two input ports that described balance is amplified photoelectric commutator 7 respectively.
5) described balance is amplified photoelectric commutator 7 and described two input polarization light intensities is subtracted each other and be converted to the output port that electric signal amplifies photoelectric commutator 7 through described balance and arrive described data acquisition unit 8.
6) data of described data acquisition unit 8 acquisitions are passed to described data processing unit 9 and are done the post analysis processing.
Above embodiment only is a better embodiment of the present invention, but protection scope of the present invention is not limited thereto, and does not break away from any modification and local replacement of spirit and scope of the invention, all should be encompassed within protection scope of the present invention.