Researchers have developed a new metasurface-based device that can produce multiple distinct holographic images depending on the surrounding medium and the wavelength of light used. The ability to store information that is only retrievable with the right set of keys—such as a certain light wavelength combined with wet conditions—could be further developed to design simple yet effective encryption devices.
Click here for original story, New metasurface-based device creates different images depending on light and environmental conditions
Source: Phys.org