How 3D Holograms Work
(via Physics Girl) Holograms are photographic recordings of 3D scenes. Unlike a camera, which captures one view through a small viewer focused by a lens, holograms capture an entire light field which allows them to recreate the 3D scene. Shimmery 2D projections, like pre-recorded Pepper’s ghost illusion, are often confused with 3D holograms.
