Guest Editorial Digital Holography for Industrial Applications

The papers in this special section focus on the technology of digital holography and presents industrial applications for its use. Optical holography is a technique developed in the 1960s for recording a three-dimensional (3-D) scene on photographic film which is commonly referred to as hologram. Being different from classic photography that captures the intensity information from a single view point, a hologram is capable of recording the entire optical waves that are scattered from a 3-D object. Theoretically, when a hologram is illuminated by a coherent beam, the 3-D image it records will be reconstructed to the observer with complete depth and disparity information. It has been anticipated by many researchers of the 3-D technology that holography is likely to be the ultimate solution for the realization of 3-D display systems. Before the emergence of high-speed computers, optical holography has also been successfully applied in various kinds of tedious signal processing tasks. Notably, it has been demonstrated that computation intensive problems like Fourier transform and correlation can be obtained instantly through an optical system of lenses with coherent illumination. Despite these encouraging factors, it turns out that the practical applications of optical holography are rather restricted. The barricade could be attributed to the high complexity of the optical system and the strict demands on the environmental conditions that are required in setting up a holographic system.