3D image reconstruction of transparent gas flow by parallel phase-shifting digital holography

The authors descrive a technique for three-dimensional (3D) imaging of transparent and dynamic object from the phase image obtained by parallel phase-shifting digital holography. The phase image of the transparent and dynamic object is recorded and reconstructed by parallel phase-shifting digital holography. Inverse Abel transform is applied to the phase image to calculate 3D image of transparent and dynamic object. The calculation result is radial distribution of the phase difference of object wave. Radial distribution of the 3D image of the object is obtained by using the radial distribution of the phase difference. Finally, by assuming that the shape of the object is axially symmetric with respect to the direction in which the object moves, the 3D image of the object is reconstructed by using the radial distribution of 3D image of the object. The technique is experimentally demonstrated to obtain the 3D image of transparent gas flow. Holograms of the transparent gas are recorded by the camera at 180,000 frames per second. 3D motion picture of the transparent gas flow, which provides the dynamic information of the inside of the object, was obtained from the holograms.