Engineering: Not your mother’s hologram

A technique for producing three-dimensional, sculpture-like moving images in ‘thin air’ is reported in this week’s Nature. Such images, which can coexist with solid objects occupying the same physical space, are currently unobtainable with holographic technologies.

Three-dimensional moving images have long been the stuff of science fiction. The appearance of three dimensions is usually created by manipulating light, but existing approaches for doing so have limitations such as narrow viewing angles and the need for special viewing headwear.

Daniel Smalley and colleagues have designed a free-space volumetric display platform - the Optical Trap Display - through which a three-dimensional object can be represented in real space and can be viewed from any angle without the use of glasses. A near-invisible light field traps and moves a small particle through a volume of space. As the particle moves, it is illuminated using red, green and blue laser light, mapping out the surface of the object to be imaged. When the particle scanning is fast enough, it gives the appearance of a solid three-dimensional surface with a large colour gamut and fine details. At even faster scanning rates, the imaged object can appear to move.