Fiber pressure sensing device based on C-shaped spring tube

Abstract

The invention discloses a fiber pressure sensing device based on a C-shaped spring tube. A multi-layer microbend element containing a signal fiber is installed on the C-shaped spring tube. When the pressure to be measured is applied to the C-shaped spring tube, the C-shaped spring tube has the tendency of rounding and extending, and the extending displacement of the C-shaped spring tube causes the compression of the multi-layer microbend element so that the bending curvature of the signal fiber contained in the multi-layer microbend element is changed, thus the power of optical signals transmitted in the signal fiber is obviously changed, and the purpose of measuring the magnitude of the pressure is achieved by utilizing a testing instrument for detection. Because the multi-layer microbend element is adopted, the effective length of the signal fiber is extended, and the bending curvature of the signal fiber is reduced, thereby improving the accuracy of the device and greatly prolonging the service life of the signal fiber simultaneously, so that the device of the invention has wide application prospects.

Description

technical field [0001] The invention belongs to a sensing device of a gas or liquid pressure measuring instrument, and in particular relates to a device based on a C-shaped spring tube and achieving the purpose of pressure sensing by detecting changes in optical fiber microbend loss. Background technique [0002] There are many types of optical fiber pressure sensing devices, mainly including light intensity modulation optical fiber sensing devices, fiber grating pressure sensing devices, optical fiber interference pressure sensing devices, etc. The latter two are characterized by sensing sensitivity However, in the actual application process, there are defects and deficiencies such as complex equipment and high operating costs, which greatly restrict the application and promotion of optical fiber sensing devices. In the optical intensity modulation optical fiber pressure sensing device, there are mainly membrane reflection type or microbending loss type structure. The main...

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Problems solved by technology

The main defect of the former is that the optical fiber is discontinuous in the sensing device, and there is a problem of end surface pollution, which affects the long-term use accuracy of the optical fiber sensing device. Loss type device, two sawtooth plates that have been strictly processed are placed in parallel, and the optical fiber is clamped between the two parallel sawtooth plates. The deformation of the optical fiber in this device is very small, only a few hundred microns, resulting in a small detection range, which limits its practicality. and scope of application; another type is Chinese patent 93206204.0 "optical fiber sensing pressure head", and the article "optical fiber based on C-type spring tube and optical fiber ring" in Journal of Xi'an University of Technology (2000) Vol.16No.1p.69-73 Proposed in "Pressure Sensor": The optical fiber disk is made into an optical fiber ring with a diameter of about 5-10mm, and placed between the fixed bracket and the C-shaped spring tube through the clamp. When there is a pressure change, the position of the C-shaped spring tube is relatively Due to the change of the fixed bracket, the bending curvature of the fiber ring is changed, resulting in the change of the bending loss of the optical signal transmitted by the optical fiber in the fiber ring. By detecting the change of the bending loss, the change of the monitoring pressure can be obtained, but in the two devices The optical fiber ring requires a diameter of about 5-10mm, and most optical fibers will have a large bending internal stress under this bending curvature, and the optical fiber will break in a short time, resulting in the failure of the optical fiber sensor. The practicality and popularization of this kind of sensor

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