Digital holography based sound propagation imaging works on phase change characteristics of a medium where sound wave propagates. Spatial and temporal distribution of sound field can be obtained by measuring phase modulation of light caused by sound field. In this technique, object wave passes near to vibrating object and the interference patterns are recorded in digital holograms as a function of time. After using numerical reconstruction by angular spectrum method and acousto-optic data processing, sound field can be visualized. This technique has been tested for vibration frequency measurement and can also visualize the human voice by optical means. It has also been used for optical voice encryption, which can secure voice. For vibration frequency measurement, Fourier analysis is used and for voice encryption, optical image encryption techniques have been utilized. In this paper, we present our proposed sound wave imaging scheme and its applications in frequency estimation and voice encryption. In the support of sound imaging scheme and its applications, we present detailed theory and experimental results.

Date Published: 7 November 2018
PDF: 7 pages
Proc. SPIE 10818, Holography, Diffractive Optics, and Applications VIII, 108180R (7 November 2018); doi: 10.1117/12.2515579

Published in SPIE Proceedings Vol. 10818:
Holography, Diffractive Optics, and Applications VIII
Yunlong Sheng; Chongxiu Yu; Changhe Zhou, Editor(s)