Touchable holograms

Check this out: http://www.alab.t.u-tokyo.ac.jp/~siggraph/09/TouchableHolography/SIGGRAPH09-TH.html

Mid-air displays which project floating images in free space have
been seen in SF movies for several decades [Rakkolainen 2007].
Recently, they are attracting a lot of attention as promising tech-
nologies in the field of digital signage and home TV, and many
types of holographic displays are proposed and developed. You can
see a virtual object as if it is really hovering in front of you. But
that amazing experience is broken down the moment you reach for
it, because you feel no sensation on your hand.
Our objective is adding tactile feedback to the hovering image in
3D free space. One of the biggest issues is how to provide tactile
sensation. Although tactile sensation needs contact with objects by
nature, the existence of a stimulator in the work space depresses the
appearance of holographic images. Therefore some kind of remote-
controllable tactile sensation is needed. That is achieved by our
original tactile display [Iwamoto et al. 2008]. The following paper
explains the technologies employed for a “Touchable Holography.”