Vivid holographic images and text can now be produced by means of an ordinary inkjet printer. This new method, developed by a team of scientists from ITMO University in Saint Petersburg, is expected to significantly reduce the cost and time needed to create the so-called rainbow holograms commonly used for security purposes to protect valuable items such as credit cards and paper currency from piracy and falsification. The results of the study were published 17 November in the scientific journal Advanced Functional Materials.
Ref: Sol-Gel Assisted Inkjet Hologram Patterning. Advanced Functional Materials (17 November 2015) | DOI: 10.1002/adfm.201503483
ABSTRACT
Hereby, it is presented for the first time a method of producing holographic text and images using inkjet printing. For this purpose, colorless TiO2 ink with a high refractive index is used and deposited on top of exposed poly(ethylene terephthalate)-based microembossed paper by an inkjet printer. Nanoscale coating the paper containing printed text or graphics with transparent polymers or lacquers provides an optical effect of selective preservation of the holographic pattern. The resulting image is preserved only at the site of the colorless ink with a high refractive index from an inkjet printer, allowing to quickly generate any image with a holographic effect. Achieving these results has succeeded through the use of a colloidal dispersion of nanocrystalline titania with a refractive index of 1.75 ± 0.08 in the entire visible range, which meets inkjet rheological requirements. It is shown that the diffraction effect and optical transparency in the visible region are fully preserved. For the first time, it is demonstrated the importance of chemically prepared nanomaterials and nanostructures for an application in the field of holography.