Patent ID: 7873273

Claim:
An apparatus for measuring the characteristics of an optical fiber, the apparatus comprising: an optical pulse generator that generates a series of first and second optical pulses from a coherent light, the first and second optical pulses having a time interval between them, the time interval being equal to or shorter than a life time of an acoustic wave in the optical fiber, the optical pulse generator emitting the series of first and second optical pulses toward the optical fiber; a detector that couples the coherent light with a Brillouin backscattered light which includes first and second Brillouin backscattered lights belonging to the first and second optical pulses respectively, thereby generating an optical signal, the detector converting the optical signal into an electrical signal; a signal processor that takes the sum of the electrical signal and a delay electrical signal which is delayed from the electrical signal by a delay time corresponding to the time interval, thereby generating an interference signal, the signal processor finding the characteristics of the optical fiber based on the interference signal; and a frequency-varying device that allows the signal processor to obtain a Brillouin spectrum from the electrical signal.