The analog–to-digital coding of relief-phase holograms using anisotropic media

The basis of the modern methods of protecting products, goods, documents, and equities are holographic security technologies, the development of which indicates that they are improving, new equipment and materials appear, new methods of hologram recording are being developed, their manufacturability is increasing, identification and authentication are being simplified. Combined images are widely used in modern holography. When creating combined images, various optical effects arise, such as moire, parallax, color change, etc., which, in combination with each other, as well as with other images (microtext, hidden images, sequential numbering, marking, coding, chemical indicators), permit to use them both to protect documents and to obtain an original artistic effect. This article discusses combined protective elements based on a relief-phase hologram with a deposited polymer carrier layer containing a latent image visible in polarized light. This protective element is named crystallogram. In the process of developing a crystallogram, the synthesis of monomers and the preparation of an anisotropic polarizable composition was mastered, a layer of polymerizable liquid crystals (PLC) was obtained with a contrast visualization of a latent image. A technology was developed for combining the relief-phase hologram with the deposited polymer carrier layer with the subsequent blocking of the polarizable liquid crystals (PLC) layer by protective varnish layers.