Patent ID: 7633052

Claim:
An impact detection system, comprising: three or more optical fiber sensors disposed respectively in different positions of a subject to be inspected, the sensors not being in alignment with one another, in which the optical fiber sensors each includes a core portion having a grating portion formed therein, the grating portion having a plurality of gratings reflecting light so that a wavelength band of reflected light changes when a distance between adjacent gratings changes, and the three or more optical fiber sensors vibrates the wavelength band depending on an elastic wave propagating through the subject; a light source to input light into the core portion, in which a spectrum bandwidth of the light includes at least a desired vibration width of the wavelength band; two or more optical filters connected to an output end of the three or more optical fiber sensors, the optical filters having different pass bands to one another with respect to an output light of one of the optical fiber sensors; and an arithmetic processing apparatus to perform arithmetic processing of output values of the three or more optical fiber sensors through the optical filters so as to specify a position on the subject where an impact is loaded, the output values being obtained when the impact is loaded on the subject, wherein the arithmetic processing apparatus measures a difference of arrival times between two elastic waves having different propagation speeds, the two elastic waves caused by the impact as a vibration source, at each of the three or more optical fiber sensors, so as to specify the position where the impact is loaded on the subject on a basis of a measurement result.