Scientists use cascading water droplets to create a 3D multilayered computer display.
A team from Carnegie Mellon University has created a multi-layered computer display for playing Tetris (or viewing/playing any other content) using sheets of cascading water droplets. The scientists projected the high resolution images onto a series of water screens, one behind the other, to give depth to the image. They said that by quickly switching between images, a projector can display on different layers at different times on this display.
New Scientist explains the waterfall display system:
Each screen is formed by water droplets falling from 50 stainless-steel needles. The needles release their droplets in unison, with 60 such lines created every second. A camera tracks their position and feeds the information to a projector, which illuminates them with pulses of light. The human eye integrates the information from several pulses to create the illusion of images moving on a floating screen.
Video of 3D Tetris played on this multilayered computer display: