SoylentNews

Fnord666 writes:

A team at Caltech has figured out a way to encode more than one holographic image in a single surface without any loss of resolution. The engineering feat overturns a long-held assumption that a single surface could only project a single image regardless of the angle of illumination.

The technology hinges on the ability of a carefully engineered surface to reflect light differently depending on the angle at which incoming light strikes that surface.

[...] Led by Andrei Faraon, assistant professor of applied physics and materials science in the Division of Engineering and Applied Science, the team developed silicon oxide and aluminum surfaces studded with tens of millions of tiny silicon posts, each just hundreds of nanometers tall. (For scale, a strand of human hair is 100,000 nanometers wide.) Each nanopost reflects light differently due to variations in its shape and size, and based on the angle of incoming light.

That last property allows each post to act as a pixel in more than one image: for example, acting as a black pixel if incoming light strikes the surface at 0 degrees and a white pixel if incoming light strikes the surface at 30 degrees.

"Each post can do double duty. This is how we're able to have more than one image encoded in the same surface with no loss of resolution," says Faraon (BS '04), senior author of a paper on the new material published by Physical Review X on December 7.

Seyedeh Mahsa Kamali et al, Angle-Multiplexed Metasurfaces: Encoding Independent Wavefronts in a Single Metasurface under Different Illumination Angles, Physical Review X (2017). DOI: 10.1103/PhysRevX.7.041056

Source: https://phys.org/news/2017-12-holograms-surface.html

Original Submission