[OPTICAL REVIEW Vol. 4, No. 1A (1997) 65-68]

Optical Fiber Coupler Array for Multi-Point Sound Field Measurements

Kentaro NAKAMURA and Koichiro FUKAYA

Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama, 226 Japan

(Received June 26, 1996; Accepted September 11, 1996)

A pressure-sensitive device using an optical fiber coupler is proposed, and is integrated into an array system to measure sound field distributions. The optical coupling between two optical fibers is modulated by the applied sound field with the use of a membrane mechanically connected to the coupler. In the array system, a large number of the optical coupler sensors are connected two-dimensionally, and sound pressure at each sensor can be read out by switching the input light sources in turn. A prototype of the basic array system based on this principle was made, and its performance was demonstrated. The signal discrimination between each element was confirmed in a 2×2 array; then, using a four-element linear array, we demonstrated the steering of beam based on the phased array method.

Key words : optical fiber sensor, optical fiber coupler, microphone array, sound field measurements, sound pressure, phased array