Scientists have created a plastic transparent screen that can turn any window into a display for moving images.
The screens, which are made by adding tiny nanoparticles that reflect blue light into a liquid polymer, can be stuck on to any window, researchers said.
The nanoparticles are invisible to humans, creating the transparency, while images projected in blue light show up.
A team from the Massachusetts Institute of Technology (MIT) and Harvard departments of Physics, and the US Army Edgewood Chemical Biological Center, developed a new approach to produce transparent projection screens.
"We literally just pour the nanoparticles into the polymer before it solidifies," said lead researcher Chia Wei Hsu, a graduate student from MIT and Harvard University, US.
Only a few thousandths of a gram of nanoparticles are needed per square centimetre of screen, meaning the technology is also relatively cheap, 'BBC News' reported.
However, since each type of particle reflects only one colour, the screens display just one colour of image.
It would be possible to have multiple colours, but the more nanoparticles that are added to the screen, the more opaque it would become, researchers said.
"Since it's so simple to deploy, you could paste this [plastic] sheet onto any surface," Hsu said.
Transparent screens have innumerable applications, from showing navigation data on car windshields and aircraft cockpit windows, to projecting information and figures on glass windows and eyeglasses, to advertising and retail, researchers said.
