It's the same thing used by Google Glass, and other head-up displays (like the ones built into airplanes and high-end cars). I believe it involves collimation: https://en.wikipedia.org/wiki/Collimated_light

For example, here's a description of the HUD currently available in several BMW cars:

http://www.bmw.com/com/en/insights/technology/technology_gui...

"The image is projected in such a way that it appears to be about two metres away, above the tip of the bonnet, making it particularly comfortable to read. BMW Head-Up Display halves the time it takes for eyes to shift focus from road to the instruments and back."

The magic of projection.

And then the projected light goes into your eyes and strikes your retina, sending signals to your brain. Amazing!