OPTICAL SENSOR SYSTEM

PROBLEM TO BE SOLVED: To provide an optical sensor system that can measure the phases of electromagnetic waves traveling in space at different measuring points and thereby to enhance the accuracy of measuring phase differences of electromagnetic waves among the measuring points.SOLUTION: In an optical sensor system 10A, when phase differences among different measuring points are to be figured out while measuring the phases of electromagnetic waves traveling in space at the measuring points with first and second photoelectric field sensors 12A and 12B, a length (L2) of a second optical fiber 31 is so controlled relative to a length (L1) of a first optical fiber 30 that a path difference ( L) of the length (L2) of the second optical fiber 31, which transmits phasic data emitted from the second photoelectric field sensor 12B, from the length (L1) of the first optical fiber 30, which transmits phasic data emitted from the first photoelectric field sensor 12A, is kept within an appropriate range for accurately measuring the phases against variations in temperature conditions at the time of phase measurement.