OPTO-ACOUSTIC SENSOR SYSTEM

PURPOSE:To make it possible to suppress the attenuation of the power of wave- split light which is inputted into a signal processing means by setting the power splitting ratio with a wave splitting coupler at the approximately constant value, and continuously connecting wave synthesizing couplers from the initial stage to the final stage with one piece of fiber. CONSTITUTION:The power of an input light pulse L is split with a wave-splitting coupler 31-1 at a splitting ratio K into the wave-split lights LS1 and LR1. The light LR1 is received with an optical fiber 34 through a wave synthesizing coupler 33-1. The light is cast into a signal processing means 20 sequentially passing through wave synthesizing couplers 33-2 to 33-(N + 1). The light LS1 is sent into a sensing coil 32-1. The optical characteristic is changed in correspondence with the sound pressure of a sound-wave signal S which is applied on the coil from the outside. The signal is delayed by a delay time T and inputted into a coupler 31-2. In the coupler 31-2, the light LS-2 is split by the same way. With respect to the light LR1 to LR(N + 1) which are cast into the means 20 at the deviation of every time T, each wave-split light is made to be double pulses with a compensator 21. The time overlap is generated between the wave- split lights. The double pulses are mixed, and interference occurs.