レーザ発振特性とレーザマイクロホンの音波検出特性の研究

Abstract

Since the vibrating film is used for a conventional microphone, the detectable frequency is restricted. Recently, the influence on the human body by the sound wave of low frequency or high frequency from various apparatuses or equipments has become a problem. It is necessary to detect the sound wave of such frequency. A new type of microphone by using self-coupling effect of semiconductor laser has been studied. It is called the laser microphone. This microphone consists of laser and a light reflector, and it is not necessary to post-process a signal. Difference in coherence reflects on the sensitivity of the laser microphone. Therefore spectrum of laser is measured. It is understood that the laser microphone becomes sensitive if coherence is better and light power is higher. The laser microphone can detect a sound with frequency to 24 kHz.