Patent ID: 7696471

Claim:
An impact detection system, comprising: an optical fiber including a core portion, the core portion including a plurality of sensor sections each provided with a grating portion, in which the grating portion is provided with a plurality of gratings each reflecting light, a wavelength band of reflected light changes when a distance between adjacent gratings changes, and the optical fiber vibrates the wavelength band depending on an elastic wave propagating through a subject to be inspected; a light source to input light into the core portion of the optical fiber, in which a spectrum bandwidth of the light includes vibration bands of wavelength bands of the sensor sections; optical filters each connected to an output terminal of the optical fiber, from which output terminal the reflected light is output; and an arithmetic processing unit to perform arithmetic processing of output values of the plurality of sensor sections through the optical filters, so as to detect an impact to the subject by measuring energy levels of elastic waves that arrive at respective optical fiber sensors, said measuring being performed by synthesizing said output values, said output values comprising information on an existence of an output, nonexistence of any outputs, an existence of time changes of an output value, nonexistence of any time changes of an output value, and a situation of time changes, wherein the wavelength bands of the sensor sections in the optical fiber are distributed to be apart from each other such that the vibration bands do not overlap with each other, and wherein pass bands of the optical filters corresponding to one of the sensor sections are distributed in the vibration band of the one sensor section, and are distributed in both sides of a center of the wavelength band of the one sensor section under no impact loaded.