Talaria was the brand name of a large-venue

video projector A video projector is an image projector that receives a video signalling (telecommunication), signal and projects the corresponding image on a projection screen using a lens (optics), lens system. Video projectors use a very bright ultra-high-per ...

from

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...

introduced in 1983. Light from a

Xenon arc lamp A xenon arc lamp is a highly specialized type of gas discharge lamp, an electric light that produces light by passing electricity through ionized xenon gas at high pressure. It produces a bright white light to simulate sunlight, with applications ...

was modulated by a

light valve A light valve (LV) is a device for varying the quantity of light, from a source, which reaches a target. Examples of targets are computer screen surfaces, or a wall screen in the case of a light projector. There are two basic principles of achievin ...

consisting of a rotating glass disc that was continuously re-coated with a viscous oil. An

electron beam Cathode rays or electron beam (e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to ele ...

similar to the one in a

cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictu ...

traced a

raster Raster may refer to: * Raster graphics, graphical techniques using arrays of pixel values * Raster graphics editor, a computer program * Raster scan, the pattern of image readout, transmission, storage, and reconstruction in television and compu ...

on the surface of the coated glass, deforming the surface of the oil. Where the oil was undisturbed, the light would be reflected into a light trap. The raster traced into the oil formed a

diffraction grating In optics, a diffraction grating is an optical component with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structura ...

. The basic unit was monochrome (PJ7000 line). Color display is accomplished in one of two ways: The single lens color projector (PJ5000 line) use

dichroic In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are abs ...

filters to separate the white light of the xenon bulb in two channels, Green and Magenta. RGB color separation and processing is obtained using vertical wobbulation of the electron beam on the oil film to modulate the green channel and sawtooth modulation is added to the horizontal sweep to separate and modulate Red and Blue channels. The optical system used in the Talaria line is a

Schlieren Schlieren ( ; , ) are optical inhomogeneities in transparent media that are not necessarily visible to the human eye. Schlieren physics developed out of the need to produce high-quality lenses devoid of such inhomogeneities. These inhomogeneitie ...

optic like an

Eidophor An Eidophor was a video projector used to create theater-sized images from an analog video signal. The name Eidophor is derived from the Greek word-roots ''eido'' and ''phor'' meaning 'image' and 'bearer' (carrier). Its basic technology was th ...

, but the color extraction is much more complex. Two units (MLV) or three units (3LV) are stacked one atop the other, each one devoted to a single color (3LV). In early models (PJ5000), the light source was a 650 watt xenon bulb (sealed beam) similar to the units in modern 35mm film projectors, and produced 250 lumens at a 75:1 contrast ratio. The later 3LV model produced as much as 3500 lumens at a 250:1 contrast ratio. The later LV series had an optional "Multiple Personality" (MP) module that would allow the projector to display various resolutions and scan rates produced by computers of the time. It could produce an 8,000 lumen image onto a 15 foot by 20 foot screen from 64 feet away.

References

{{Thermionic valves Projectors

See also

References