Patent ID: 7995198

Claim:
An optical fiber characteristic distribution sensor, comprising: a light source system for outputting probe light and pumping light; a phase difference adjusting section for adjusting the phase difference between the probe light and the pumping light outputted from the light source system; an optical fiber section at least part of which is placed in an object to be measured and both ends of which are optically connected to the light source system such that the probe light is inputted from one end thereof and the pumping light is inputted from the other end thereof, said optical fiber section including a marker portion where, as reference data relating to the shape of the Brillouin gain spectrum of the probe light that has obtained gain due to the Brillouin scattering that occurs accompanying the propagations of the probe light and the pumping light, data relating to the shape of the Brillouin gain spectrum has been preliminarily measured in a state where the optical fiber section is placed in a normal state; a spectrum measuring section for receiving the probe light that has obtained the gain due to the Brillouin scattering that occurs accompanying the propagations of the probe light and the pumping light as the outputted light from the optical fiber section, and for measuring data relating to the shape of the Brillouin gain spectrum that the received probe light has obtained due to the Brillouin scattering; a phase difference offset calculating section for calculating a difference between the phase difference at the time of measurement between the probe light and the pumping light at the time that the Brillouin gain spectrum that reflects the gain that has occurred in the marker portion is measured by the spectrum measuring section, and the reference phase difference between the probe light and the pumping light at the time that the reference data relating to the marker portion is measured; a position calculating section for determining the occurrence position of the Brillouin gain spectrum measured by the spectrum measuring section; a characteristic calculating section for extracting characteristic information of each portion in the optical fiber section from the data relating to the shape for each Brillouin gain spectrum measured by the spectrum measuring section; and a characteristic distribution calculating section for calculating the characteristic distribution along the longitudinal direction of the optical fiber section, from the information about the occurrence position calculated by the position calculating section together with the information about the characteristics calculated by the characteristic calculating section, wherein the phase difference adjusting section adjusts the phase difference between the probe light and the pumping light outputted from the light source system by shifting the scanning range of phase difference by a difference value that is calculated by the phase difference offset calculating section.