Holograms printed from inkjet printer in minutes
Wed 25 Nov 2015
Russian scientists have developed a new method for printing rainbow holograms from a standard inkjet printer, hoping to significantly reduce cost and time limitations of traditional methods.
The new technique, designed at ITMO University in Saint Petersburg and outlined in scientific journal Advanced Functional Materials, aims to improve the process of printing holograms used in security applications, such as protecting credit cards and paper currency from forgery.
Project lead Alexander Vinogradov, senior research associate at the International Laboratory of Solution Chemistry of Advanced Materials and Technologies (SCAMT) at ITMO, described loading an inkjet printer with a colourless ink made of nanocrystalline titania. “The peculiarity of our ink is high refractive index in all visible range of light,” said Vinogradov.
Once deposited on a microembossed sheet of paper, and covered with varnish or polymer layer, the ink creates a unique patterned image. The complete method allows tailored holographic images to be printed in just a few minutes, rather than a number of days, as seen with current technologies.
Despite the use of holographic images in security practices since the 1960s, the technology remains plagued with challenges which prevent it from further application. Aleksandr Yakovlev, the study’s author, explained: “The conventional way of preparing a hologram is incredibly time consuming and consists of several stages. First, one needs to create a master hologram, which is usually laser recorded on a thin layer of photosensitive polymer. The polymer is then dried and washed out to get rid of unexposed parts.
“The resulting stencil is then transferred to a metallic matrix, which eventually serves to emboss holographic microrelief on the surface of a transparent polymer film.”
According to the researcher, this entire process can take up to several days. It is only now that printing holographic images can be achieved in a “quick and effective manner.”