Light Field Labs has raised an additional US $28 million in funding to develop and produce free air holographic display technology. They are said to have a working prototype now and the additional funding will enable them to scale up to an actual product.

“The aim is to create holographic objects that appear to be three dimensional and float in space without head-mounted gear such as augmented reality or virtual reality goggles.”

Source: Light Field Labs : 3D Holograms no glasses Deep Dive – fxguide

The principle people behind the technology had developed the Lytro camera technology. As best I can tell, it may be similar to a digital implementation of a conventional, analog, film-based hologram. In the original hologram technology, you look at a flat image that is, basically, like a window pane. As you move to the left or right, you see the true 3D image visible from that point in space. In the laser-based hologram, the window pane is a film that has recorded light interference patterns.

From the description down the page, here, my interpretation is they have created a currently small window pane that is replicating the light interference hologram concept, but in the digital domain. Obviously, it takes a tremendous amount of computational horsepower and for video, high bandwidth, both of which are becoming available as tech advances.

I presume, also, that this technology can be used to project objects in front of the viewing plane, as is done in stereoscopic 3D. In other words, actors or objects can be appear to be between you and the viewing screen – or behind the screen.

This tech creates true 3D that does not require glasses for viewing.