How Do Holograms Work?

A hologram is created by splitting a laser beam into two paths: one (the reference beam) goes directly to a photographic plate, while the other (the object beam) bounces off the subject first. When the two beams meet at the plate, they create an interference pattern — a complex pattern of light and dark fringes that encodes both the intensity and the phase (direction) of the light waves reflected from the object. Unlike a photograph, which captures only intensity, the hologram preserves depth information. When the developed hologram is illuminated with a similar laser, the interference pattern reconstructs the original light field, producing a 3D image that changes perspective as you move your viewpoint.