Fiber bragg grating osmometer

Abstract

The invention discloses a fiber bragg grating osmometer which comprises a shell, a pressure bar, grating and a transmission optical fiber, wherein the shell is provided with a pressure inlet hole and an optical fiber lead hole, and the pressure inlet hole is provided with a filter screen; the shell is provided with a membrane which can directly sense the pressure at the pressure inlet hole; the two ends of the pressure bar are connected with the membrane, the grating is buried inside the pressure bar, and the transmission optical fiber is led out through the optical fiber lead hole. When in use, pore water enters into the osmometer through the pressure inlet hole and acts on the membrane to lead the membrane have deflection deformation; meanwhile, the pore water is transformed into concentrated force and acts on the pressure bar, and external force is applied on the pressure bar to lead the pressure bar to stretch; when the grating is under the pressure, the central wavelength is changed. At this time, a fiber bragg grating demodulation device is used for detecting the central wavelength of the grating, and software can be used for acquiring and storing data, so that osmotic pressure detection can be realized. The fiber bragg grating osmometer has the advantages of high measuring accuracy, small volume, electromagnetic interference resistance, good waterproof performance, capability of long-term monitoring, etc.

Description

technical field [0001] The invention relates to a fiber grating osmometer and belongs to the field of fiber grating sensing. Background technique [0002] As we all know, one of the most difficult issues in the safety monitoring of dams, tunnels and coal mines is to reliably determine the location of the seepage area. Only by quickly and accurately ascertaining the location and flow of seepage (leakage) can effective prevention and repair be taken Therefore, seepage location and quantitative monitoring of seepage volume are of great significance. [0003] Since the 1980s, a lot of manpower and material resources have been invested at home and abroad to carry out research on monitoring (detection) technology for leak location. The basic principle is to detect whether there are obvious differences in physical properties (that is, electrical properties, elasticity, temperature, etc.) between the hidden danger and the surrounding rock soil, concrete and other media, or the vari...

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Problems solved by technology

[0006] Many research institutions have started research on optical fiber osmotic pressure sensors. Wu Yonghong et al. designed a dual-fiber reflective hydraulic osmotic pressure sensor with high measurement accuracy, but the design principle and manufacturing process are very complicated; Tong Guoguo et al. invented the double diaphragm box reflective sensor. The pressure sensor has a simple structure but a small range; Xia Yuanyou et al. designed a fiber grating osmotic pressure sensor based on polyurethane elastic material, which is used in civil engineering such as highway soft foundations, but the repeatability of the elastic material is poor

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