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Fiber grating distributed strain sensor and strain monitoring method thereof

A technology of distributed strain and optical fiber grating, which is applied in the direction of using optical devices to transmit sensing components, transmission monitoring/testing/fault measurement systems, cladding optical fibers, etc., and can solve difficult to realize networking, complex demodulation algorithms, system structure Complicated problems, to achieve high spatial resolution positioning and improve measurement accuracy

Active Publication Date: 2011-05-11
杭州光学精密机械研究所
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This system has a complex structure and requires complex demodulation algorithms, making it difficult to implement networking

Method used

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  • Fiber grating distributed strain sensor and strain monitoring method thereof
  • Fiber grating distributed strain sensor and strain monitoring method thereof
  • Fiber grating distributed strain sensor and strain monitoring method thereof

Examples

Experimental program
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Effect test

Embodiment 2

[0083] Embodiment 2, the networking system scheme based on wavelength division multiplexing is as follows Figure 4 Shown: where 1 is the light source module, using such as figure 1 The tunable laser 11 used in the structure is formed by connecting an acousto-optic modulator 12 and a radio frequency modulator 13, and outputs an optical pulse sequence. 2 is an optical connector. 3 for figure 1 Fiber optic rings in the structure. 411, 412, 413, 414... 41r are cascaded fiber grating sequences connected to the ring-down cavity through the circulator 33, and the access mode of 411 is the same as figure 1 The fiber grating sensing unit 4 in the structure is the same, and other fiber gratings are sequentially cascaded and welded behind the 411 fiber grating. Through this structure, distributed strain sensing within the gate area of ​​multiple fiber gratings can be realized, and the distributed strain demodulation method in the gate area of ​​each fiber grating is exactly the same...

Embodiment 3

[0086] Embodiment 3, the networking system scheme based on wavelength division multiplexing plus time division multiplexing is as follows Figure 5 Shown: where 1 is the light source module, and Figure 4 The same light source used in the structure. 31, 32, ..., 3j are as figure 1 The fiber optic ring formed in the structure. 411, 412, ... 41r; 421, 422, ... 42r; ...; 4j1, 4j2, ..., 4jr are respectively the cascaded fiber grating sequence groups connected to the optical fiber ring 31, 32 ... 3j, each stage The construction method of the fiber grating sequence is the same as that of Figure 4 The construction method is the same in the wavelength division multiplexing structure. Each optical fiber ring and the corresponding cascaded fiber grating sequence constitute a measurement channel, 2 are s optical switching channels, and the number of optical switching channels can reach 16 or even 32 channels. Using optical switching, one channel is selected each time, which channel ...

Embodiment 4

[0088] Example 4, Image 6 It is one of the performance optimization schemes for the network system structure. In the basic structure of distributed sensing figure 1 and network structure Figure 4 Add a filtering and denoising function module on the basis of , and mainly draw the access scheme of the filtering and denoising function module, and other undrawn parts are consistent with the previous scheme. A filtering fiber grating 8 is connected to the ring-down cavity through a second optical circulator 34 . Along the transmission direction of the light pulse in the ring-down cavity, the second optical circulator 34 is connected after the first optical fiber circulator 33 . The filter fiber grating 8 is fixed on the stress tuning or temperature tuning device, and is connected to the tunable laser 11 through the automatic synchronous trigger device 9, so as to keep the wavelength output by the light source consistent with the center reflection wavelength of the filter fiber ...

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Abstract

The invention relates to a fiber grating distributed strain sensor and a strain monitoring method thereof, which are characterized in that an erbium-doped fiber amplifier is added into an optical fiber fading cavity to form an active fading cavity, and an optical pulse fading sequence is obtained, so the positioning accuracy of submillimeter-magnitude spatial length measurement can be realized; and a wavelength of a tunable laser is in one-to-one correspondence with positioning data of fiber grating bragg reflection space by taking a linear chirped fiber grating or a uniform fiber grating as a sensing device, and the corresponding local strain capacity is demodulated by positioning the variable quantity of a local bragg reflection wavelength to realize distributed strain sensing. In the fiber grating distributed strain sensor, the spatial resolution ratio is improved to a submillimeter magnitude by a direct time domain measurement method, and the fiber grating distributed strain sensor has a compact structure and simple algorithm, can perform on-line monitor in real time and can be used for networking, so that the fiber grating distributed strain sensor has the large application space in the field of optical fiber sensing.

Description

technical field [0001] The invention relates to an optical fiber distributed sensor, in particular to an optical fiber grating distributed strain sensor based on optical fiber ring-down cavity technology and a strain monitoring method thereof. Background technique [0002] Optical fiber sensors have many advantages such as strong anti-electromagnetic interference, high sensitivity, good electrical insulation, safety and reliability, corrosion resistance, and can form an optical fiber sensor network, so they have broad applications in various fields such as industry, agriculture, biomedicine, and national defense. Application prospects. [0003] There are currently several technical solutions for fiber optic strain sensors, including Fiber Bragg Grating (Fiber Bragg Grating, FBG), Long Period Grating (Long Period Grating, LPG), Mach-Zehnder Interferometer (MZ-I) , fiber optic Sagnac ring, etc. The strain sensor based on fiber grating has the characteristics of high sensitiv...

Claims

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Application Information

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IPC IPC(8): G01D5/353G02B6/02G02B6/26H04B10/08H04B10/07
Inventor 甘久林郝蕴琦叶青潘政清蔡海文瞿荣辉方祖捷
Owner 杭州光学精密机械研究所
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