| 摘要 |
PROBLEM TO BE SOLVED: To detect invasion by climbing up or jumping over a fence, and to detect a wide range of intrusions by dispensing with a large-scale constitution of facilities. SOLUTION: A plurality of types of FBGs (grating sections) having a different diffractive index in fiber glass are provided at a fixed interval in the longitudinal direction of optical fibers 12, 13A, 13B. The optical fibers are laid between the upper posts or on the surface of a fence 10. Reflection waves from each FBG are led with respect to light input to the optical fibers by photodetectors 14, 15A, 15B. Further, the position of the FBG whose wavelength has been shifted is detected by the swaying of the optical fibers due to the stress applied to the fence by using a wavelength shift detector 16. A pattern recognition device 19 fetches the position of each wavelength-shifted FBG as the difference in the timing of each pulse signal, and identifies the swaying of the fence by the intrusion from that of the fence by other factors, such as wind, based on the output pattern of the pulse signal. COPYRIGHT: (C)2006,JPO&NCIPI |
