Boffins at the University of Tokyo have developed 3D holograms that can be touched with bare hands Dubbed the Airborne Ultrasound Tactile Display, the hologram projector uses an ultrasound quirk called acoustic radiation pressure to create a pressure sensation on a user's hands. This information is tracked with two Nintendo Wiimotes. It means that the user doesn't use any direct contact and so doesn't dilute the quality of the hologram.

Top boffin Hiroyuki Shinoda showed off the technology at SIGGRAPH 2009 in New Orleans. It uses a retroreflective marker is attached on the tip of user's middle finger. IR LEDs illuminate the marker and two Wiimotes sense the 3D position of the finger. Owing to this hand-tracking system, the users can handle the floating virtual image with their hands.

The researchers can dribble a virtual bouncing ball, feel virtual raindrops bouncing off their hand, and feel a small virtual creature crawling on their palm. The researchers hope that the technology will have applications in video games, 3D CADs, and other uses. We would have thought the porn industry would be the killer app.