To solve the trouble wherein it is difficult to make decision, even if abnormalities of Bragg grid sensor and a fault occurs though detection of an external force by an intruder, etc. or an optical fiber can be performed by measuring the amount of wavelength shifts of the Bragg grid sensor and a polarization wave fluctuation are measured with an infiltration detector of a conventional optical fiber sensor, and moreover, to solve the trouble that it is also difficult to decide whether a system carries out normally an operation, since there is no inspection function of Bragg grid sensor nor an optical source for optical fibers with the infiltration detector of a conventional optical fiber sensor.
Entering of light is carried out for the optical fiber, having a plurality of Bragg grid sensors by which Bragg lattice spacings differ, and spectrum by each wavelength of returning the light reflected by each of the Bragg grid sensor is detected. The fault of the Bragg grid sensor is inspected, by comparing the spectrum with the reference level of each of this detected wavelength.
NAGASHIMA MASAHIRO
MOGI ATSUSHI
| JP2004170313A | 2004-06-17 | |||
| JP2005241402A | 2005-09-08 |
Tadahiko Inaba
Kanako Murakami
Nakatsuru Kazutaka