Optical microphone based on a reflective micromirror diaphragm

Abstract

An optical microphone incorporating a reflective diaphragm and a fiber-optic head is demonstrated. The diaphragm is made of a micromirror membrane which is suspended by a silicon bar connected to a frame, allowing for displacement induced by acoustic waves. A compact and simple optical head is implemented by exploiting a single multimode fiber. For the assembled microphone, the static characteristics are investigated in order to find the operation point, defined as the optimum distance between the head and the diaphragm, and a flat frequency response with a variation of ∼2 dB for the range of 0.1 to 2 kHz is accomplished. © 2006 Wiley Periodicals, Inc.