Image from paper Fairy Lights in Femtoseconds — Source
This kind of display acts in a similar way to Volumetric Projection, but it is considerably more dangerous and expensive. There are only one or two companies working on this display type right now, and one is Aerial Burton. There is limited information on how this display actually works, so take my layman’s explanation with a grain of salt. This display technique works by focusing high powered lasers onto a point in space. When the energy at that point gets hot enough, the air molecules get ionized and release some photons. Aside from ionized plasma, fluorescence is one, and cavitation is another when involving a fluid medium. Here is a demonstration video of the Aerial Burton display:
Two forms of Aerial Burton’s displays — one with a fluid based medium and one based entirely in air — Source
This display unfortunately has many drawbacks that are similar to those of a laser projector. They still work by moving a mirror very quickly, so there is a limited number of points that they can draw at a given time. There is also an added crackling noise component because of the tiny explosions needed to make the visuals. These tiny explosions can also emit an ozone gas that can be potentially harmful if used in an enclosed space.
Another set of researchers in Japan have been working on a much smaller implementation of this same technique that they are calling the Fairy Lights display system. The primary difference is that this version is touchable. By firing the lasers much faster than the Aerial Burton method, the images are smaller and not as bright, but much safer. The tangible element can be used as an additional cue for interaction with the display. They still have similar drawbacks related to visual fidelity (number of dots per second) and added popping noise (their paper says about 22dB of noise is added when using the display). Here is a video featuring some of the interactions and visuals that can be produced.
Image from paper on Fairy Lights in Femtoseconds — Source