Visualization of sound field using Optical Wave Microphone coupled with computerized tomography

The novel method, which we call the “Optical Wave Microphone (OWM)” technique, is based on a Fraunhofer diffraction effect between sound wave and laser beam. The light diffraction technique is an effective sensing method to detect the sound and is flexible for practical uses as it involves only a simple optical lens system. In this work, fibered OWM which is improved in signal-noise ratio of the conventional OWM, was developed. This new method can realize high accuracy measurement of slight density change of atmosphere. Moreover, fibered OWM can be applied for sound field visualization by computerized tomography (CT) because the ultra-small modulation by the sound field is integrated along the laser beam path.