OPTICAL FIBER STRAIN SENSOR AND ITS MANUFACTURING METHOD AND METHOD FOR MEASURING STRUCTURE USING OPTICAL FIBER STRAIN SENSOR

摘要

PURPOSE: To accurately obtain the amount of deformation and strain of a structure from the amount of light transmission loss and to obtain a sensor which can be easily mounted to the structure by spirally forming an optical fiber being closely adhered to the inner-periphery surface of a metal pipe. ;CONSTITUTION: A spiral optical fiber 2 is inserted into a metal pipe (for example, one made of stainless steel) 1 being inscribed inside the pipe in the optical fiber strain sensor 1'. The optical fiber 2 is in single or multiple mode and the entire surface of optical fiber is covered with a primary jacket. In the optical fiber 2, it is important to set the initial radius of curvature to a specific value. Then, a strain is generated in the metal pipe 1 according to the strain generated in a pipeline 4 and the amount of transmission loss of light generated from a light source 6 is measured by a power meter 7 according to the change in the radius of curvature of the optical fiber 2. Then, the radius of curvature is calculated from the relationship between the radius of curvature of the optical fiber 2 and the amount of light transmission loss and then the strain of the metal pipe 1 is calculated, thus obtaining the distortion of the pipeline 4.;COPYRIGHT: (C)1997,JPO