General Electric Light Valve for the Talaria video projector
Tube modulateur de lumière pour vidéoprojecteur
Lichtventil für Videoprojektor
This is certainly the weirdest vacuum tube in my collection: it contains an electric motor, a spinning disc, and oil!
Shortly after World War II, GE Electronics Department General Manager, Dr. Baker bought the rights to a Swiss developed
projection television system called Talaria. The Talaria approach made use of a rotating optically-flat glass disc with a thin film of oil
squeegeed over a deposited transparent conductive coating. This film was then raster-scanned in a vacuum by an electron beam which was
modulated by a video signal as in a standard television picture tube. The electric field in the oil film between the deposited electrons
and the conductive coating result in a decreased oil film thickness, the effect being more pronounced where a greater number of electrons
were deposited. By mounting this disc in a Schlieren optical system
and shining a light from a Xenon arc lamp through the scanned image on the oil film, the thickness variation on the oil film was converted
into a variation of light intensity so as to project a bright television image on a screen. The properties of the oil used were adjusted
so its image decayed in the time between television frames in the same manner as the luminescent decay of a picture tube phosphor.
The Talaria principle was developed by a General Electric commercial business into a successful line of television
projectors for theater or other large screen use.
Hauteur • Height • Höhe : 29 cm • 11" 4/10
Diamètre • Diameter • Durchmesser : 22,5 cm • 8" 93/10
The Talaria video projector
The oil in the bottom of the tube
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