Move over Tu-Pac, Touchable Holograms are the new thing

Yoichi Ochiai is a researcher at Japanese company Digital Nature Group, that has created holograms using femtosecond lasers that are not only safe to touch but are holograms you can interact with.

The holograms themselves are created using a laser that sends out ultra-short bursts of light. The technical terms for how ultra-short they are is referred to as femtoseconds (a quadrillionth of a second) – pretty short, right? The laser is then focused on air molecules, giving them just enough energy to ionize and create light called plasma.

The ability to interact with this plasma happens when someone touches the plasma, triggering a programmed change, like checking a box. Digital Nature Group calls the displays that the lasers create “fairy lights” because the lights are so small that they kind of look like they were made by pixies.

Touching the plasma is similar to touching sandpaper so it’s not completely invisible like more holograms. The fact that there is an actual sensation associated with the hologram opens doors to many new possibilities. Maybe not at the level of something like tractor beams and lightsabers just yet, but it’s a step closer to the types of things you see in sci-fi movies.

If you want the real technical explanation of how the touchable holograms work, they lay it out in their YouTube page as follows:

We present a method of rendering aerial and volumetric graphics using femtosecond lasers. A high-intensity laser excites a physical
matter to emit light at an arbitrary 3D position. Popular applications can then be explored especially since plasma induced by a femtosecond laser is safer than that generated by a nanosecond laser. There are two methods of rendering graphics with a femtosecond laser in air: Producing holograms using spatial light modulation technology, and scanning of a laser beam by a galvano mirror. The holograms and workspace of the system proposed here occupy a volume of up to 1 cm^3; however, this size is scalable depending on the optical devices and their setup. This paper provides details of the principles, system setup, and experimental evaluation, and discussions on scalability, design space, and applications of this system. We tested two laser sources: an adjustable (30-100 fs) laser which projects up to 1,000 pulses per second at energy up to 7 mJ per pulse, and a 269-fs laser which projects up to 200,000 pulses per second at an energy up to 50 ¹J per pulse. We confirmed that the spatiotemporal resolution of volumetric displays, implemented with these laser sources, is 4,000 and 200,000 dots per second. Although we focus on laser-induced plasma in air, the discussion presented here is also applicable to other rendering principles such as fluorescence and microbubble in solid/liquid materials.