Fairy Lights Holography: Japanese Researchers Develop a Safe Open-Air Interactive Hologram

A research team from Tsukuba University in Japan has announced their development of an apparatus that is capable of projecting open-air holograms that are safe for humans to interact with.

While the practice of modern holography was invented in 1962, the holograms produced were imprinted on clear glass or plastic sheets, and required the viewer to look through that medium to view the holographic image itself. Open-air holography methods using fast-pulsing lasers have been developed in recent years, but the images themselves were hazardous, as the plasma generated in the air to produce the image was hot enough to burn human skin.

The Tsukuba University research team, headed by Dr. Yoichi Ochiai, made their breakthrough using what is called a femtosecond laser, or a laser that pulses at one millionth of one billionth of a second. Dubbing their new method "Fairy Lights", this apparatus allows the generation of small, free-floating 3D virtual objects that can be safely interacted with by humans. The images are made up of a series of "voxels" (pixels that have volume) projected by the focused laser, and can be directly interacted with, since they form a physical plasma suspended in the air. Currently, the images are limited to 8mm (1/3rd inch) in size, since they must be smaller than the objective lens on the apparatus, and can be projected up to one meter (40 inches) from the lens. Dr. Ochiai reports that the plasma from the images feels like sandpaper to the touch.

“People’s daily lives would change if we use a bigger laser in a bigger space where people can interact with it, and to see how it can be used in situations where three-dimensional communication is necessary such as a construction site or in the medical field,” envisions Dr. Ochiai.