Sound wave detection by common-path digital holography

Abstract

The sound wave has been recorded and visualized by optical means such as digital holography (DH), where light wave carries the sound information. However, in DH, an additional reference beam is required, which can create problems in the applications where long-distance propagations are required for sound field studies. In this work, we present a new way of sound wave recording and visualization by a common-path DH in which a single light beam can carry the sound information and near the recording device, this single light beam is divided into the object and reference beams by using a beam splitter. One of the beams is filtered to generate a clean reference beam. Therefore, this configuration of DH eliminates the need of a reference beam from the starting point and makes the system simpler, compact, and stable, in comparison to the optical sound wave recording setup of traditional DH. The presented optical system of sound wave recording is suitable for applications where the single beam is required to observe invisible sound phenomena at far position. We present experimental results of vibration frequency and voice information visualization to demonstrate the proposed system.