Researchers at MIT have come up with a new approach that could have significant advantages over existing systems for transparent displays.
The new system embeds nanoparticles in the transparent material. These tiny particles can be tuned to scatter only certain wavelengths, or colors, or light, while letting all the rest pass right through. The glass remains transparent enough to see colors and shapes clearly through it, while a single-color display is clearly visible on the glass.
The researchers demo this by projecting a blue image in front of a scene containing cups of several colors, all of which can clearly be seen through the projected image.