Printing Custom Holograms in Minutes

Security feature can now be produced using an ordinary inkjet printer.

An example of an inkjet printed hologram. (Image courtesy of ITMO University.)

An example of an inkjet printed hologram. (Image courtesy of ITMO University.)

The technology for creating holographic images has existed since the 1960s, but technical difficulties have impeded its spread and integration into manufacturing.

This is unfortunate because holographic images can be valuable tools, not only for protection against counterfeiting but also for identification in automated conveyor systems.

However, a recent breakthrough has enabled researchers to print holographic images using an ordinary inkjet printer, significantly reducing both the time and cost of creating holograms.

Holographic Printing: Then and Now

The conventional method for creating a hologram consists of several stages. First, a master hologram is laser-recorded on a thin layer of photosensitive polymer. The polymer is then dried and washed out to remove the unexposed parts.

The resulting stencil is then transferred to a metallic matrix, which serves to emboss holographic microrelief onto the surface of a transparent polymer film. This entire process can take several days.

Moreover, preparing the master hologram requires meeting certain rigid stipulations, including temperature control and vibration isolation.

An alternative process using a colorless ink made of nanocrystalline titania was developed by Alexander Vinogradov and Aleksandr Yakovlev at IMTO University in St. Petersburg, Russia.

The ink can be loaded into an ordinary inkjet printer and deposited onto special microembossed paper, which is then covered with varnish.

The resulting holographic image appears exclusively in the areas where the ink was deposited.

“The peculiarity of our ink lies in its high refractive index in all visible range of light,” said Vinogradov. “The use of nanocrystalline ink forms a layer with high refractive index that helps preserve the rainbow holographic effect after the varnish or a polymer layer is applied on top.”

This novel approach makes it possible to print custom holographic images on transparent film in minutes rather than the days required for conventional methods.

Are Inkjet Holograms a Security Risk?

Although this new technique makes it possible to print holograms of practically any size for less money in less time, it’s not yet clear whether this constitutes an overall boon or risk for manufacturing.

One of the reasons holograms have been used in security applications is because they are difficult to forge. This feature is a consequence of their manufacturing process: conventional holographic images are replicated from a master hologram, which is expensive and requires specialized equipment.

In contrast, although the inkjet holograms still require special ink and paper, the fact that they can be produced at a much lower cost and much more quickly suggests that this new process could ultimately devalue holograms as a security tool.

On the other hand, low-cost holograms could have a positive impact on inventory control and quality assurance in the packaging industry. Smaller manufacturers could have access to the same technology used by their larger competitors.

Ultimately, the crucial question is whether inkjet holograms will be as secure as their conventional counterparts.

For more information, view the article published in the materials science journal, Advanced Functional Materials.