Parallel Phase-Shifting Digital Holography Capable of Simultaneously Capturing Visible and Invisible Three-Dimensional Information

We propose a parallel phase-shifting digital holography capable of simultaneously capturing both outside three-dimensional (3D) information of the object such as a surface of an object which human being can perceive (visible information) and internal 3D information of the object (invisible information) using a visible laser light and an invisible laser light. This technique can carry out phase-shifting interferometry for each light with a single-shot exposure, because an interference fringe image in which the information of each light and each phase-shift is spatially multiplexed is recorded by a phase-shifting array device and a wavelength-filter array. We numerically simulated the proposed technique, and the effectiveness of the proposed technique was shown by evaluating the simulation results using a correlation coefficient. Also we conducted a preliminary experiment using a red filter and a near-infrared filter placed 8 cm apart from each other as objects containing both visible and invisible 3D information. A He-Ne laser operated at 633 nm and a diode laser operated at 830 nm were used as a visible light source and an invisible light source, respectively. The 3D imaging capability of the proposed technique was successfully demonstrated by the preliminary experiment, and the validity of the technique was also confirmed by evaluating root mean square errors of the reconstructed images. Also the capability for simultaneously 3D capturing of outside (visible) information and internal (invisible) information was demonstrated by a preliminary experiment.