| 摘要 |
<p>PROBLEM TO BE SOLVED: To reliably detect a position where a physical phenomenon occurs, its type, magnitude or the like by including, in electromagnetic waves propagating in at least a second half of a path, other electromagnetic waves which can be distinguished from electromagnetic waves propagating in a first half of the path. SOLUTION: Light with a wavelength ofλ1 from a light source 30 among light reaching a detector 150 through an optic fiber 1b is led via a light wave divider 70 to a measurement system 221, and light with a wavelength of 22 from a light source 31 is led to a measurement system 222, respectively. Then they are respectively divided into x-polarized waves and y-polarized waves, so that in respective received signal processing parts 251, 252, waveforms S1t and S2t such as a square root of a squared sum of reception results of orthogonal polarized waves are obtained. The waveform S1t is a received signal with a wavelength ofλ1 via optic fibers 1a, 1b from the light source 30, and S2t is a received signal of a wavelength ofλ2 via the optic fiber 1b from the light source 31. Then polarized fluctuation waveforms due to a physical phenomenon functioning to the fibers 1a, 1b are obtained in a waveform separating part 80, and a functioning position and time of the physical phenomenon functioning to the fibers 1a, 1b are obtained in a signal recognition part 53.</p> |
