CN104535007A - Distributed type optical fiber strain measurement system based on cavity-length-adjustable F-P white light interference demodulating device - Google Patents

Abstract

The invention belongs to the technical field of optical fiber sensing, and specifically relates to a distributed optical fiber strain measurement system based on an adjustable cavity length FP white light interference demodulation device, which can be used for real-time monitoring and measurement of physical quantities such as multi-point quasi-distributed strain or quasi-temperature distribution. . The invention consists of a wide-spectrum light source, a four-port optical fiber circulator, a fiber coupler connected by two ports, an adjustable cavity length FP white light interference demodulation device, a three-port optical fiber circulator, a first transmission optical fiber and a second transmission optical fiber, a first The optical fiber sensor array and the second optical fiber sensor array, the first photodetection signal amplifier and the second photodetection signal amplifier, and the first signal processing unit and the second signal processing unit are composed. Due to the use of the optical fiber circulator, the feedback back to the light source is eliminated. The signal improves the stability of the light source, enhances the utilization rate of the power of the light source, and further improves the multiplexing capability of the sensing system.

Description

A Distributed Optical Fiber Strain Measurement System Based on F-P White Light Interferometric Demodulation Device with Adjustable Cavity Length

technical field

The invention belongs to the field of optical fiber sensing technology, and specifically relates to a distributed optical fiber strain based on an adjustable cavity length F-P white light interference demodulation device that can be used for real-time monitoring and measurement of physical quantities such as multi-point quasi-distributed strain or quasi-temperature distribution. measuring system.

Background technique

One of the advantages of fiber optic white light interferometers is that they can be multiplexed easily. Multiple sensors have only a single optical interference signal within their respective coherence lengths, so more complex time or frequency multiplexing techniques are not required to process the signals. In recent years, white light interferometric sensing technology has developed vigorously. One of the hot spots is the development of a variety of optical fiber sensors and test systems based on multiplexing technology for the measurement of physical quantities such as strain, temperature, and pressure. The development background of multiplexing technology is mainly due to the fact that in actual measurement and testing applications, the sensing of a single physical quantity and a single location point is far from meeting people's requirements for the perception of the whole thing or the system state, which often requires multiple Or the distribution of multi-point physical quantities can be measured online or in real time. For example, in the process of non-destructive testing and monitoring of large structures (hydropower stations, dams, bridges, etc.) and other information to extract. Therefore, the number of sensors is usually dozens or hundreds. If the test system is only connected with a single point sensor, the test cost will undoubtedly be greatly increased, and the system reliability will be reduced at the same time. Using multiplexing technology, the same demodulation system is used to query the measurement information of multiple sensors, which not only greatly simplifies the complexity of the system, but also ensures the measurement accuracy and reliability. At the same time, due to the multiplexing technology, the cost of the single-point sensor is reduced, so that the test cost is greatly reduced, the cost performance is improved, and the fiber optic sensor has more advantages than the traditional sensor.

White light interferometric optical fiber sensors can effectively avoid the limitations and problems encountered by signals with long coherence lengths in the case of narrowband laser sources. A major advantage of space-division multiplexed white-light interferometric fiber optic sensors is the ability to measure absolute lengths and time delays. In addition, due to the short coherence length of the sensing signal, the time-varying interference of system stray light can be eliminated. Another advantage of space-division multiplexing white-light interferometry is that multiple sensors can be coherently multiplexed into one signal without the need for relatively complex time-division multiplexing or frequency-division multiplexing techniques. The space division multiplexing technology is realized by using a scanning interferometer (such as a Michelson interferometer) to match the optical paths of the signal light and the reference light. If the optical paths of the two signal lights match, white light interference fringes will be observed in the output signal of the interferometer. It can realize high-precision absolute measurement, and the parameters that can be measured include position, displacement, strain and temperature.

In practical applications, especially in the monitoring of building structures, long-distance, multi-point quasi-distributed measurements of building structures are usually required. However, for the conventional fiber-optic white-light interferometer structure, the length of the sensing fiber is limited by the adjustment range of the variable scanning arm. In addition, even if a long-distance adjustment range can be obtained, the transmission loss of the optical signal in the long-distance spatial optical path will be very large.

In order to solve the above problems, in 1995, Wayne V.Sorin and Douglas M.Baney of H-P Company of the United States disclosed a multiplexing method of a white light interference sensor based on an optical path autocorrelator (US Patent: Patent No. 5557400), based on a Michelson interferometer Structure, the optical path autocorrelation is achieved by using the optical path difference formed between the fixed arm and the variable scanning arm of the Michelson interferometer by the optical signal and the optical path difference between the reflected optical signals of the front and rear two end faces of the optical fiber sensor to achieve the optical path autocorrelation. The white light interference signal is used to change the path difference between the scanning arm and the fixed arm to match each sensor in a plurality of end-to-end serial optical fiber sensor arrays one by one to complete the multiplexing of optical fiber sensors.

In addition, the low-coherence twisted Sagnac-like optical fiber deformation sensing device disclosed by the applicant in 2007 and 2008 (Chinese patent: 200710072350.9) and the space-division multiplexing Mach-Zehnder cascaded optical fiber interferometer and measurement method (Chinese patent No.: ZL 200810136824.6) is mainly used to solve the problem of anti-destruction during the layout of fiber optic sensor multiplexing arrays; the combined measuring instrument of the optical fiber Mach-Zehnder and Michelson interferometer array disclosed by the applicant in 2008 (Chinese patent: ZL 200810136819.5) and Twin array Michelson optical fiber white light interference strainmeter (Chinese patent number: ZL200810136820.8) is mainly used to solve the temperature interference in the multiplexing of white light optical fiber interferometer, and the simultaneous measurement of temperature and strain; the applicant disclosed in 2008 A simplified multiplexing white light interference optical fiber sensing and demodulation device (Chinese patent: ZL 200810136826.5) and a distributed optical fiber white light interference sensor array based on an adjustable Fabry-Perot resonant cavity (Chinese patent: ZL 200810136833.5), introducing a ring Cavity and F-P cavity optical path autocorrelators are mainly used to simplify the topology of multiplexing interferometers, construct a common optical path, and improve temperature stability; a dual-reference length low-coherence optical fiber ring network disclosed by the applicant in 2008 The introduction of sensor demodulation device (Chinese patent application number: 200810136821.2) 4×4 fiber optic coupler optical path autocorrelator aims to solve the problem of simultaneous measurement of multiple reference sensors.

However, in the above-mentioned interferometer structure based on space division multiplexing, the light source power attenuation is large and the utilization rate of the light source is low. Only a small part of the light emitted by the light source reaches the sensor array and is received by the detector to form an interference signal. In terms of the optical path structure disclosed by W.V.Sorin, when the optical signal reflected by the sensor array passes through the fiber coupler 1, only half of the light enters the Michelson autocorrelator, while the other half of the light is lost along the optical path connected to the light source. In addition, when the light entering the Michelson autocorrelator is reflected by the mirror and passes through the coupler 2, only half of the light enters the photodetector, and the other half of the light is fed back into the coupler 1. Therefore, only 1/4 of the power of the light source contributes to the sensing process in this structure. In addition, the light fed back through the coupler 1 will directly enter the light source. Although the light source used is a wide-spectrum light, it is not very sensitive to the feedback compared with the laser light source, but the excessive signal power feedback is especially for SLD and ASE For a light source with a large spontaneous radiation gain, the feedback light will cause a large noise of the light source.

Contents of the invention

The purpose of the present invention is to provide a distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interferometric demodulation device with simple and compact structure and easy operation and adjustment.

The purpose of the present invention is achieved like this:

Distributed optical fiber strain measurement system based on F-P white light interferometric demodulation device with adjustable cavity length, consisting of wide-spectrum light source 1, four-port optical fiber circulator 2, fiber coupler 3 with dual-port connection, F-P white light interferometric demodulation with adjustable cavity length Device 4, three-port optical fiber circulator 5, first transmission optical fiber 6 and second transmission optical fiber 7, first optical fiber sensor array 8 and second optical fiber sensor array 9, first photodetection signal amplifier 10 and second photodetection signal amplifier 11 and the first signal processing unit 12 and the second signal processing unit 13, the light emitted by the spectrum light source 1 is injected into the cavity length adjustable F-P white light interference demodulation device 4 via the fiber coupler 3 after passing through the four-port optical fiber circulator 2 , F-P white light interferometric demodulation device with adjustable cavity length generates two beams of interrogation optical signals with adjustable optical path difference, respectively pass through the three-port optical fiber circulator and the four-port optical fiber circulator, and then pass through the first transmission optical fiber 6 and the second transmission optical fiber 7 It is sent into the first optical fiber sensor array 8 and the second optical fiber sensor array 9, the interference signal light reflected by the first optical fiber sensor array 8 passes through the first transmission optical fiber 6 again, and is detected by the first photoelectricity through the three-port optical fiber circulator 5 The signal amplifier 10 receives and amplifies the signal, and the signal is finally processed by the first signal processing unit 12 to give the measurement result; the interference signal light reflected by the second optical fiber sensor array 9 passes through the second transmission optical fiber 7 again, and loops through the four-port optical fiber The sensor 2 is received and amplified by the second photodetection signal amplifier 11, and finally processed by the second signal processing unit 13 to give the measurement result.

The F-P white light interferometric demodulation device with adjustable cavity length is to couple a Sagnac ring optical path structure with an F-P fiber interferometer with adjustable cavity length through two dual-port 2×2 fiber couplers respectively. The F-P fiber interferometer An optical fiber coated with a total reflection mirror 42 at one end is connected to an optical fiber self-focusing lens collimator 43 at the other end. The optical fiber self-focusing lens collimator is fixed on the base of a precision slide stage, and a plane optical reflection The mirror 44 is fixed on a slidable platform, facing the fiber self-focusing lens collimator, forming an F-P interferometer with adjustable optical path.

The fiber optic sensor array is composed of a basic fiber optic sensor array, and the fiber optic sensor array is composed of several fiber optic sensors connected in series from end to end. Each fiber optic sensor is composed of a single-mode fiber of any length. The fiber optic sensor array It is to form a series of single-mode fiber segments of different lengths into a serial array connected end to end or to add a strobe connection of a 1×M multi-channel optical fiber switch to construct M optical fiber sensor arrays into M linear arrays for roving detection. Optical fiber sensor array or through 1×N, N=2, 3, 4... optical fiber star couplers to form bus-type optical fiber sensing network topology, star optical fiber sensing network topology and composite star optical fiber sensing network topology .

The beneficial effects of the present invention are:

The invention discloses a low coherence multiplexing distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interference demodulation device. It can be used for real-time monitoring and measurement of physical quantities such as multi-point quasi-distributed strain or quasi-temperature distribution, and can be widely used in large-scale intelligent structural health monitoring and other fields. It uses a Sagnac fiber structure to connect an F-P interferometer with adjustable cavity length as a demodulation interferometer to the optical path of the system. By using two fiber optic circulators to connect the fiber optic sensor array and the photodetector, all the signals reflected by the fiber optic sensor are coupled to the photodetector. Compared with the prior art, due to the use of the fiber optic circulator, the feedback feedback The signal of the light source improves the stability of the light source, and at the same time enhances the utilization rate of the power of the light source, enabling all the light emitted by the light source to be utilized, and further improves the multiplexing capability of the sensing system.

Description of drawings

Figure 1 is a schematic structural diagram of a low-coherence multiplexing quasi-distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interferometric demodulation device.

Fig. 2 is a schematic structural diagram of an F-P white light interference demodulation device with adjustable cavity length.

Figure 3(a) is a schematic diagram of the topology of a linear array optical fiber sensing network, and Figure 3(b) is a schematic diagram of a topology of a switch-type parallel linear array optical fiber sensing network.

Fig. 4 is a schematic diagram of the topology of the optical fiber strain sensor array network.

Fig. 5 is a schematic diagram of a system embodiment in which two optical fiber sensor arrays adopt simple linear arrays in a low-coherence multiplexing quasi-distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interferometric demodulation device.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

The invention provides a distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interference demodulation device. It is characterized in that it consists of a wide-spectrum light source 1, a four-port optical fiber circulator 2, a dual-port connected optical fiber coupler 3, an adjustable cavity length F-P white light interference demodulation device 4, a three-port optical fiber circulator 5, a transmission fiber 6 and 7. Optical fiber sensor arrays 8 and 9, photodetection signal amplifiers 10 and 11, and signal processing units 12 and 13. The invention can be used for real-time monitoring and measurement of physical quantities such as multi-point quasi-distributed strain or quasi-temperature distribution, and can be widely used in the fields of large-scale intelligent structure health monitoring and the like.

Figure 1 is a schematic structural diagram of a low-coherence multiplexing quasi-distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interferometric demodulation device. Broad-spectrum light source 1, four-port optical fiber circulator 2, fiber coupler connected by two ports 3, cavity length adjustable F-P white light interferometric demodulation device 4, three-port optical fiber circulator 5, transmission optical fibers 6 and 7, optical fiber sensor array 8 and 9, photodetection signal amplifiers 10 and 11, and signal processing units 12 and 13.

Fig. 2 is a schematic structural diagram of an F-P white light interference demodulation device with adjustable cavity length. The white light interference demodulation device couples a Sagnac ring optical path structure with an F-P fiber interferometer with adjustable cavity length through two dual-port 2×2 fiber couplers 3 and 41 respectively, wherein the F-P fiber interferometer is composed of One end is coated with the optical fiber of total reflection mirror 42, and the other end is connected with an optical fiber self-focusing lens collimator 43, and this optical fiber collimator 43 is fixed on the base of a precision slide stage, and a plane optical reflector 44 It is fixed on a slidable platform, facing the fiber collimator 43, and constitutes an F-P interferometer with adjustable optical path.

Figure 3(a) is a schematic diagram of the topology of a linear array optical fiber sensing network, and Figure 3(b) is a schematic diagram of a topology of a switch-type parallel linear array optical fiber sensing network.

Fig. 4 is a schematic diagram of the topology of the optical fiber strain sensor array network. The fiber optic sensor network used in the system is composed of basic fiber optic sensor arrays, and the fiber optic sensor array is composed of several fiber optic sensors connected in series from end to end. Each fiber optic sensor is composed of a section of arbitrary length, two It consists of a single-mode fiber with a fiber ferrule at the end. A series of single-mode optical fiber segments of different lengths are formed into a serial array connected end to end, and a linear array of optical fibers is formed through a 1×N (N=2, 3, 4…) optical fiber star coupler as shown in the figure Sensor network topology, bus fiber optic sensor network topology, star fiber optic sensor network topology and composite star fiber optic sensor network topology.

Figure 5 is a schematic diagram of a system embodiment in which two optical fiber sensor arrays use simple linear arrays in a low-coherence multiplexing quasi-distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interferometric demodulation device, 8 in the figure , 9 is a linear optical fiber sensor array.

The quasi-distributed optical fiber strain measurement system consists of a wide-spectrum light source 1, a four-port optical fiber circulator 2, a dual-port connected optical fiber coupler 3, an adjustable cavity length F-P white light interference demodulation device 4, a three-port optical fiber circulator 5, and a transmission It consists of optical fibers 6 and 7, optical fiber sensor arrays 8 and 9, photodetection signal amplifiers 10 and 11, and signal processing units 12 and 13. The light emitted by the wide-spectrum light source 1 in the system is injected into the cavity length adjustable F-P white light interference demodulation device 4 through the four-port optical fiber circulator 2 and then through the dual-port optical fiber coupler 3. The interference demodulation device generates an optical path difference The adjustable two beams of interrogation optical signals are sent to the optical fiber sensor arrays 8 and 9 through the transmission fibers 6 and 7 after passing through the three-port optical fiber circulator 5 and the four-port optical fiber circulator 2 respectively, and the interference signals reflected by the sensor array 8 The light passes through the transmission fiber 6 again, is received by the photodetector 10 through the three-port optical fiber circulator 5 and is amplified, and the signal is finally processed by the signal processing unit 12 to give a measurement result; at the same time, it is reflected back by the sensor array 9 The interference signal light passes through the transmission fiber 7 again, is received by the photodetector 11 through the four-port optical fiber circulator 2 and is amplified, and the signal is finally processed by the signal processing unit 13 to give the measurement result.

Since the optical fiber sensor array is formed by connecting N sections of optical fibers end-to-end in series, a sensing array composed of N optical fiber sensors is formed. The lengths of each sensing fiber are l ₁ , l ₂ , ..., l _N , which are close to the length of the two optical path differences L ₀ generated in the cavity-length-adjustable FP white light interferometric demodulation device. The length of each fiber is different, and satisfy the following relationship

nL ₀ +X _j ＝nl _j ,j=1,2...N (1)

In the formula, n is the refractive index of the fiber core, and there is l _i ≠ l _j , so there is Xi _≠ X _j , that is to say, each sensor corresponds to its own independent spatial position, when a distribution is applied on the sensing fiber formula stress, the length of each sensor changes from l ₁ to l ₁ +Δl ₁ , l ₂ to l ₂ +Δl ₂ ,..., l _N to l _N +Δl _N , then the distributed strain can be obtained as

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;l</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Through repeated scanning of the optical path change, for any i-th sensor, the change of sensor length l _i can be obtained by measurement Divide by the known length l _i to measure the average strain on each section of fiber.

In order to realize the adjustment of optical path difference and scan matching, the present invention constructs an F-P white light interference demodulation device with adjustable cavity length, as shown in FIG. 2 . The white light interference demodulation device couples a Sagnac ring optical path structure with an F-P fiber interferometer with adjustable cavity length through two dual-port 2×2 fiber couplers 3 and 41 respectively, wherein the F-P fiber interferometer is composed of One end is coated with the optical fiber of total reflection mirror 42, and the other end is connected with an optical fiber self-focusing lens collimator 43, and this optical fiber collimator 43 is fixed on the base of a precision slide stage, and a plane optical reflector 44 It is fixed on a slidable platform, facing the fiber collimator 43, and constitutes an F-P interferometer with adjustable optical path. The white light interference demodulation device has two functions, one is to divide the incident beam into two paths with a certain optical path difference, and the other is to adjust the cavity length of the F-P interferometer by moving the optical mirror, thereby changing the distance between the two beams of light signals The optical path difference realizes the matching measurement of the optical path change of each optical fiber sensor in the optical fiber sensor array.

In order to further expand the quantity of optical fiber sensors, the present invention can also increase the number of optical fiber sensing arrays to M arrays in the system shown in Fig. The gating connection of M optical fiber sensor arrays containing N optical fiber sensors in each column is constructed into an N×M optical fiber sensor matrix, as shown in Figure 3.

In order to meet the requirements of various sensing measurements, the demodulation system adopted in the present invention can adapt to various optical fiber sensing network structures. We know that the fiber optic sensor network is composed of a basic fiber optic sensor array, and the fiber optic sensor array is composed of a number of fiber optic sensors connected in series from end to end. The fiber optic ferrule consists of a single-mode fiber. A series of single-mode optical fiber segments of different lengths are formed into a serial array connected end to end, and through a 1×N (N=2, 3, 4...) optical fiber star coupler, a bus type as shown in Figure 4 can be formed. Optical fiber sensing network topology, star optical fiber sensing network topology and composite star optical fiber sensing network topology.

Fig. 5 shows an embodiment of a low-coherence multiplexing quasi-distributed optical fiber strain measurement system based on an adjustable cavity length F-P white light interferometric demodulation device. The system is composed of a wide-spectrum light source 1, a four-port optical fiber circulator 2, a fiber coupler connected by two ports 3, an adjustable cavity length F-P white light interference demodulation device 4, a three-port optical fiber circulator 5, transmission fibers 6 and 7, and optical fiber Sensor arrays 8 and 9 , photodetection signal amplifiers 10 and 11 and signal processing units 12 and 13 are composed. The light emitted by the wide-spectrum light source 1 in the system is injected into the cavity length adjustable F-P white light interference demodulation device 4 through the four-port optical fiber circulator 2 and then through the dual-port optical fiber coupler 3. The interference demodulation device generates an optical path difference The adjustable two beams of interrogation optical signals are sent to the optical fiber sensor arrays 8 and 9 through the transmission fibers 6 and 7 after passing through the three-port optical fiber circulator 5 and the four-port optical fiber circulator 2 respectively, and the interference signals reflected by the sensor array 8 The light passes through the transmission fiber 6 again, is received by the photodetector 10 through the three-port optical fiber circulator 5 and is amplified, and the signal is finally processed by the signal processing unit 12 to give a measurement result; at the same time, it is reflected back by the sensor array 9 The interference signal light passes through the transmission fiber 7 again, is received by the photodetector 11 through the four-port optical fiber circulator 2 and is amplified, and the signal is finally processed by the signal processing unit 13 to give the measurement result.

When the system is working, the adjustable cavity length F-P white light interferometric demodulation device will scan and match each optical fiber sensor with different lengths by adjusting the optical path difference and scanning matching. The white light interference demodulation device has two functions, one is to divide the incident beam into two paths with a certain optical path difference, and the other is to adjust the cavity length of the F-P interferometer by moving the optical mirror, thereby changing the distance between the two beams of light signals The optical path difference realizes the matching measurement of the optical path change of each optical fiber sensor in the optical fiber sensor array.

8 and 9 in the system are two simple linear fiber optic sensor arrays. Each fiber optic sensor array is composed of a series of standard single-mode fibers cut into roughly equal lengths of fiber segments and cascaded. Each segment of fiber The lengths are all different L _i ≠ L _j i,j=1,2,...,N, at this time each section of optical fiber can be regarded as an independent length micro-deformation measuring instrument, which forms a quasi-distributed optical fiber measurement system , as shown in Figure 5. This system can be used for quasi-distributed strain measurement, and can also be used for quasi-distributed temperature measurement. It can be widely used in the field of intelligent structural health monitoring of civil engineering.

Claims (3)

1. the distributive fiber optic strain measuring system based on the long adjustable F-P white light interference demodulating equipment in chamber, by wide spectrum light source (1), four fiber port circulators (2), the fiber coupler (3) that dual-port connects, the long adjustable F-P white light interference demodulating equipment (4) in chamber, three fiber port circulators (5), first Transmission Fibers (6) and the second Transmission Fibers (7), first fibre optic sensor arra (8) and the second fibre optic sensor arra (9), first photodetection signal amplifier (10) and the second photodetection signal amplifier (11) and the first signal processing unit (12) and secondary signal processing unit (13) composition, it is characterized in that: the light that wide spectrum light source (1) sends grows adjustable F-P white light interference demodulating equipment (4) via four fiber port circulators (2) by being injected into chamber by fiber coupler (3), two bundles that the long adjustable F-P white light interference demodulating equipment in chamber produces optical path difference adjustable inquire light signal, the first fibre optic sensor arra (8) and the second fibre optic sensor arra (9) is admitted to by the first Transmission Fibers (6) and the second Transmission Fibers (7) respectively through after three fiber port circulators and four fiber port circulators, the interference signal light reflected by the first fibre optic sensor arra (8) is again by the first Transmission Fibers (6), received via three fiber port circulators (5) by the first photodetection signal amplifier (10) and be exaggerated, signal provides measurement result after being processed by the first signal processing unit (12), the interference signal light reflected by the second fibre optic sensor arra (9) is again by the second Transmission Fibers (7), received via four fiber port circulators (2) by the second photodetection signal amplifier (11) and be exaggerated, providing measurement result finally by after secondary signal processing unit (13) process.

2. a kind of distributive fiber optic strain measuring system based on the long adjustable F-P white light interference demodulating equipment in chamber according to claim 1, it is characterized in that: the long adjustable F-P white light interference demodulating equipment in described chamber a Sagnac ring light line structure and a long adjustable F-P fibre optic interferometer in chamber is of coupled connections respectively by two dual-port 2 × 2 fiber couplers, F-P fibre optic interferometer is wherein coated with the optical fiber of completely reflecting mirror (42) by one end, the other end is connected with an optical fiber GRIN Lens collimating apparatus (43), optical fiber GRIN Lens collimating apparatus is fixed on the pedestal of an accurate slippage platform, planar wave catoptron (44) is fixed on can on the platform of slippage, face optical fiber GRIN Lens collimating apparatus, constitute the F-P interferometer that a light path is adjustable.

3. a kind of distributive fiber optic strain measuring system based on the long adjustable F-P white light interference demodulating equipment in chamber according to claim 1, it is characterized in that: described fibre optic sensor arra is made up of basic fibre optic sensor arra, the Fibre Optical Sensor that fibre optic sensor arra is then connected in series successively by several head and the tail forms, each Fibre Optical Sensor is then made up of the arbitrary single-mode fiber of a segment length, fibre optic sensor arra is that the gating single-mode fiber section that a series of length does not wait being formed end to end serial array or increase by 1 × M multi-channel optical fibre switch connects M linear optical fiber sensor array M Optical Fiber Sensing Array being configured to a circling measurment or by 1 × N, N=2, 3, 4 ... Optical Fiber Star Couplers forms bus type optical fiber sensing network topological structure, star fiber optic sensor network topology structure and composite star-shaped optical fiber sensing network topological structure.