The word holography comes from the Greek words “holos” meaning “whole" and ”graphos” meaning "message". Holography is the method to record and replay a three-dimensional image of three-dimensional object in the form of hologram. A hologram can be produced by the interference between an optical field scattered by a coherently illuminated object and a reference wave.
Unlike the conventional analogue hologram which need to set an actual object and record on holographic film using optical system, digital hologram can generate any arbitrary 3D object not limited to real object, and does not rely on the availability of optical setting or specialized holographic recording materials. It digitalize the fringe pattern data calculated by CGH(computer generated hologram), then the hologram image can be produced by writing the digital data on a light modulating media.
JLab has a technique to make a digital hologram by designing 3D model of virtual objects as well as real objects, and calculating the fringe pattern called CGH, then it writes the digital data of CGH on a glass or film by lithography.