Holography: Computer Generated Holograms

A hologram is a tool for shaping the amplitude and the phase of a light wave. Shaping the amplitude distribution is easy, one way is by a photographic plate, another way is by binary pixels as used in "half-tone printing”. The phase distribution can be shaped by RE-fraction on a thin film of variable thickness, or by DIF-fraction on a diffraction grating that has been distorted on purpose.