What Can Micro-Optics Learn from Holographics?

In this excerpt from July’s ‘Authentication Insights ’ - renowned security hologram producer, De La Rue, asks what can micro-optics learn from holographics?

Both micro-optics and holographic technologies used in secure documents today have their origins dating back to the second half of the previous century.

Micro-optic products first appeared in the mid to late 1980s, when lens-based lenticular devices became popular as novelty items fabricated using injection moulding, such as for greeting cards, advertising posters and bookmarks.

Lenticular displays

The process for making lenticular displays was quite time consuming, requiring a selection of images from an animated sequence to be aligned precisely with a lenticular lens made from a sheet of transparent material with a series of thin, parallel semi-cylindrical lenses on one side and a flat surface on the other side.

The processed images were then printed onto the backside of the lenticular lens. This was typically done using specialised printing techniques such as lithography or inkjet printing. Each image was divided into thin strips or vertical interlaced columns, which were aligned with the corresponding lenses on the lenticular sheet.

Once the images were printed, they had to be aligned precisely with the lenticular lens. This was done by carefully positioning the printed sheet onto the lens, ensuring that each image strip aligns with the corresponding lenses. The alignment was crucial to maintaining the integrity of the visual effect.

After the alignment, the printed sheet and the lenticular lens were usually bonded together using an adhesive to create a single composite unit.

The technology migrated into security applications as it became thinner, with smaller lenses and thinner print lines eventually reaching the point where the technology could be integrated into banknote paper as a security thread in the mid-2000s.

Holograms (and other diffractive devices and reflective surface relief micro-structures) had novelty applications from the 1970s then started protecting security documents as patches on financial cards in the 1980s and banknotes in the late 1980s and 1990s. They eventually evolved into other product formats for other security documents.

Holograms have therefore had a bit of a head start on micro-optics when it comes to security document applications.

The inherent thinness of the foil which carries the holographic effects and the relatively low cost of holograms led to them quickly scaling to be used on a wide range of passports, banknotes, and brand protection solutions.

For identity documents, ICAO 9303 specifically recommends a holographic element to be used to protect the bio-data page of all passports to avoid counterfeit attacks, with most passports incorporating a hologram.

In the brand protection space holograms are by far the most frequently selected technology for any brand protection token.

Looking ahead

The development of new and advanced effects, coupled with strong design and integration of the physical token, has been key to ensuring holograms remain a strong visual deterrent to counterfeiting. As we look forward, the design, effects, and integration of secure holograms will continue to evolve and stay ahead of the counterfeiters.

With their earlier entrance into applications into secure documents, holograms have already gone through a cycle of patents expiring and new generations of patents being generated.

In contrast, the first wave of significant micro-optic patents for security applications will start to expire next year. It will be interesting to see the next generation of micro-optic patents as they emerge.