Science Fair Project Encyclopedia
A volumetric display device is a graphical display device that forms an image in three-dimensional volume,as opposed to the planar image of the traditional display technique. Volumetric displays are currently in a prototype phase, with a variety of systems proposed and in use in small quantities mostly in academia and various research labs.
Types of Displays
Many different attempts (US Patent Office) have been made to extend the dynamic 2D representation of the cathode ray tube to three dimensions. Volumetric displays fall into the following categories
The principle is to have a 2D lighted surface sweep in a circle, creating a volume. The image on the 2D surface (created by projection, LEDs or other techniques) changes as the surface rotates. Due to the persistence of vision humans perceive a volume of light. The lighted surface needs to be translucent. Example products are from Holoverse
Emissive volume display
This is probably the most 'direct' form of volumetric display. A volume of space is created out of active elements that are transparent in the Off state but are either opaque or luminous in the On state. When the elements or voxels are activated they show a solid pattern within the space of the display. An example of such as display is the Univ. Texas Prototype. Another kind, over lapping with the Laser Display, is the Laser Excited volume display  where lasers are focused at appropriate points in a block of optically active material. The focused action of the lasers excites the atoms in the optically active material and causes them to glow.
Varifocal mirror display
Companies Selling Volumetric Displays
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