METHOD OF MEASURING DISTANCE TO DAMAGED AREA OF FIBRE-OPTIC LIGHT GUIDE Russian patent published in 1996 - IPC

FIELD: measurement technology. SUBSTANCE: electric pulse sequences are transformed into short optical pulses. Optical pulse stream is separated to reference and probing pulses. Probing pulses are directed to tested light guide and reflected pulses are received. Pulse repetition sequence is increased till achieving stable coincidence of reference pulses with received reflected pulses. Repetition frequency F1 of coincided pulses is measured and half-period of sequence of the pulses is measured. Received reflected pulses are delayed for time being less than half-period of their repetition. Then pulse repetition frequency is reduced till achieving moment of coincidence of delayed reflected pulses with reference pulses. Coinciding pulses repetition frequency F2 is measured and reference pulses are delayed for the same time as for reflected pulses. Then pulse repetition frequency is increased once more till achieving moment of coincidence of delayed reference pulses with reference pulses. After that coinciding pulse repetition frequency F3 is measured. Distance to damaged area of fibre-optic light guide is calculated from results of measurements of F1, F2 and F3 frequencies. EFFECT: improved precision of measurement. 2 dwg