Volumetric display
A volumetric display device is a graphical display device that forms a visual representation of an object in three physical dimensions, as opposed to the planar image of traditional screens that simulate depth through a number of different visual effects. Although first postulated in 1912, and a staple of science fiction, volumetric displays are still under development, and have yet to reach the general population. With a variety of systems proposed and in use in small quantities — mostly in academia and various research labs — volumetric displays remain accessible only to corporations and the military.
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 simplest and most popular method, 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 onto the surface, LEDs embedded in the surface, 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.
- Actuality Systems
- Felix 3D
- Holoverse
- Volumetric Display Using Light Emitting Diodes — Proposed version that uses LEDs embedded in a rotating surface (University College Sedaya International)
Emissive volume
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.
Laser
A related type 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.
- Laser display — Uses two infrared lasers to stimulate atoms in a special glass, which then re-emit visible light photons with the summed energy of the two infrared photons.
Varifocal mirror
- U.S. patent 4,607,255 — Three Dimensional Display Using a Varifocal Mirror
Laser plasma
Uses a focused pulsed infrared laser (about 100 pulses per second; each lasting a nanosecond) to create balls of glowing plasma at the focal point in normal air. The focal point is directed by two moving mirrors and a sliding lens, allowing it to draw shapes in the air. Each pulse creates a popping sound, so the device crackles as it runs. Currently it can generate dots anywhere within a cubic metre. It is thought that the device could be scaled up to any size, allowing for 3D images to be generated in the sky.
See also
Science fiction
External links
- Volumetric Displays — Summary of history, practical issues, and state of the art