The holographic color prints can be easily verified, according to the researchers, but are difficult to imitate.
The prints consist of nano 3D printed polymer structures and can be used in optical document security. Information in the prints is encoded only in the surface relief of a single polymeric material, so nanoscale 3D printing could then be used to mass manufacture customized masters by nanoimprint lithography. The researchers also created an algorithm that takes multiple images as its input and generates an output file to determine the positions of different phase and colored filter elements. They then used a nanoscale 3D printer to create a holoscopic print of painter Luigi Russolo’s 1910 painting “Perfume.” The color print is visible under ambient white light. Different thicknesses of polymerized cuboid were used to modulate the phase plates and form three multiplexed holograms, projected as a red thumbprint, a green key, and blue letters that read “SECURITY.” The images were embedded within the print.