Advanced Optical Microphone

This paper introduces a new type of optical microphone that is characterized by structural simplicity and low cost, while retaining all the features offered by more expensive technologies such as laser interferometry. Operation of the new microphone relies on a reflective pattern that is etched on one side of the microphone's diaphragm. An image of the pattern is captured by a charge-coupled device, and pattern recognition is performed in real time to determine the diaphragm's instantaneous position. Hence, the complex task of detecting the minute variations in the diaphragm's position are performed by cheap, high speed optical electronics rather than by means of interferometry as shown in the literature.