At Digital Nature Group they used a type of laser, called the femtosecond laser, to accomplish the feeling that you’re touching something while touching a hologram.
While this kind of laser has been used before in aerial plasma 3D graphics demonstrations, now it is safe for the human touch for the first time. This has been accomplished by reducing the duration of laser bursts, which are now higher resolution femtoseconds, and previously they have been in lower resolution femtoseconds and nanoseconds.
The team has filmed a demonstration video, and in it you can see a finger touching the holograms with no harm whatsoever. The holograms are made of voxels, which are little points of light that plasma emits when the laser focus ionizes the air. Some of the holograms we have seen include a little heart, a star, and a fairy as well – they are mere 3D representations of 2D images, but this technology could also be used for more complicated things as well.
The research team stated they would look forward to seeing their invention used for aerial holographic interfaces (sadly, no holodeck for now!), and the public will have the opportunity to view their femtosecond laser-based volumetric displays in August on the Siggraph 2015 exhibition.