Patent ID: 8264677

Claim:
An optical path monitoring device comprising: a measurement unit which irradiates optical pulses to an optical path as a monitoring target to cause back scattered lights, the measurement unit generating measurement data based on the back scattered lights; and a processing unit which controls operation of the measurement unit, the processing unit acquiring the measurement data from the measurement unit, the processing unit performing an arithmetic processing of the measurement data to identify an abnormal point of the optical path, and the measurement unit outputting an interruption to the processing unit after generating the measurement data, the interruption indicating that the measurement data has been generated, after acquiring the interruption from the measurement unit and before completing the arithmetic processing, the processing unit sending the measurement unit instructions to start the next measurement the processing unit generating differential data representing differences between the measurement data and reference data, the measurement data being acquired during measurement, the reference data being acquired by irradiating the optical pulses to the optical path free from abnormality, and the processing unit identifying, as the abnormal point, a value included in the differential data, the identified value exceeding a threshold value.