A fog display, fog screen, vapor screen or vapor display is a system that uses haze machines or water vapor to create a semi-transparent wall, or "curtain" of suspended particles which trapped in a thin sheet (laminar flow) of air and are illuminated by a projector, [1] in order to produce a display whose images seem to float in mid air. [2] Several commercial systems exist, such as FogScreen, Displair and Heliodisplay. There is also an open-source variant being developed called Hoverlay II [3] [4]
This system can be expanded using multiple projectors to create a three-dimensional image, thus becoming a volumetric 3D display. [5] Alternatively, a three-dimensional image can be produced using a single projector paired with a reconfigurable fog screen, which generates fog at variable depths and positions. [6] [7]