Apple recently patented a 3D hologram display system that will make use of digital images and a gesture-based system. Officially, the US Patent and Trademark Office published Apple's application for "Interactive three-dimensional display system." Rather than making use of a physical object, this system will be able to display a holographic image from the use of two parabolic mirrors. What really makes this interesting is that the image can then be manipulated via a touch-activated interface that uses lasers.
There is news that Amazon may soon be releasing a smartphone with a 3D display features, so it seems Apple is already hot on its heels, even if this kind of technology is still years away.