Very cool indeed.

Fire up the *holo-deck* this stuff is getting real, and fast!

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Fairy Lights: Hologram-Like 3D Images In The Air That You Can Touch

Technology News, Videos/July 1, 2015/by Giulio Prisco/

Japanese researchers from the University of Tsukuba, Utsunomiya University, Nagoya Institute of Technology, and the University of Tokyo have developed a "Fairy Lights" display system that creates touchable hologram-like images in midair, IEEE Spectrum reports.

The Fairy Lights display uses lasers pulses fired at high frequency to ionize air molecules in midair, creating bright pixels that float in space and give tactile feedback when touched. Such systems, which have existed for a few years, are produced by companies like Japan-based Aerial Burton. However, the tactile feedback given by "traditional" laser-induced plasma displays is a bit too strong - the floating plasma that they generate will severely burn your fingers if you try to touch it.

The Fairy Lights researchers have solved the problem by using femtosecond lasers with a pulse duration of only a few tens of femtoseconds (one femtosecond is one millionth of one billionth of one second), much shorter than the nanosecond (one billionth of one second) pulses used in previous applications.

Fairy LightsThe User Feels an Impulse on the Finger as if the Light has Physical Substance

The research results are detailed in a paper submitted to ACM Transactions on Graphics. A draft version of the paper, titled "Fairy Lights in Femtoseconds: Aerial and Volumetric Graphics Rendered by Focused Femtosecond Laser Combined with Computational Holographic Fields," is freely available on arXiv.

"Our system has the unique characteristic that the plasma is touchable," notes the research paper. "It was found that the contact between plasma and a finger causes a brighter light. This effect can be used as a cue of the contact. One possible control is touch interaction in which floating images change when touched by a user."

“Shock waves are generated by plasma when a user touches the plasma voxels. Then the user feels an impulse on the finger as if the light has physical substance.
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Virtual and Augmented Reality systems like the Microsoft HoloLens can display images and 3D holograms floating in virtual air in front of the user, and even give tactile feedback via haptic gloves, but the holograms don't really exist - they are but pixels generated by a computer device. On the contrary, the Fairy Lights system generates physical pixels that can be touched with the bare fingers.

Touchable laser-induced plasma display technology is very young and the tiny pixels in the images and video are but a first rough demonstrator. However, the researchers envisage future refinements of their technology that could permit creating life-like, high-resolution, touchable 3D displays in the air.

Images from Yoichi Ochiai, Kota Kumagai, Takayuki Hoshi, Jun Rekimoto, Satoshi Hasegawa, and Yoshio Hayasaki.