Digital Holographic Recording in Amorphous Chalcogenide Films

Abstract

After the invention of holography and development of hologram micro-embossing, mass replication of hologram became possible. Use of a hologram as a security option for valuable documents and products was soon realized and won a large-scale application, which did not hinder development of other security features though. A great variety of other diffractive microstructures commonly known as diffractive optically variable image devices (DOVID) has appeared. Alongside the development of computer technology, digital holographic recording in applied holography has acquired a wide range of application. Nowadays, various types of digital holograms are used for protection and identification of industrial products and documents against counterfeiting, as well as for packing and decorating. Now two optical technologies for digital recording of protection holograms and DOVID, having similar principle of image formation, are widely used: dot-matrix and image-matrix holographic recordings (Pizzanelly, 2004). A dot-matrix hologram consists of an array of fine diffractive dots holding an image together (Fig. 1a). Each dot in such a hologram consists of a uniform diffraction pattern in which the grating pitch and grating orientation