Flying Spot Scanner Views

General Goods

Telecines that use a monochrome CRT as the light source can be referred to as flying-spot scanners. The advantage of the FSS technique is that as colour analysis is done after scanning, simple dichroics may be used to split the light to each photomultiplier — and there are no registration errors, as would have been introduced by early electronic cameras.

Historically, flying-spot scanners were also used as primitive live-action studio cameras at the dawn of electronic television, in the 1920s.[1][2] A projector equipped with a spinning perforated disc created the spot that scanned the stage. Scanning a subject this way required a completely dark stage, and was impractical for production use, but gave early researchers a way to generate live images before practical imaging pickup tubes were perfected.

Flying-spot scanner technology was later implemented by DuMont Laboratories for their Vitascan color television system, released in 1956. Vitascan produced NTSC color video using a camera that acted in reverse by housing the flying-spot CRT which was projected through the camera 's lens and illuminated the subject in a special light-tight studio. The light from the CRT camera was then picked up by special scoops housing 4 photomultiplier tubes (2 for red, 1 for green, and 1 for blue), which then would provide video of the talent in the studio. Unlike earlier FSS systems that relied on the studio being entirely darkened, Vitascan used a special strobe light would illuminate the studio for the talent's convenience, and would turn on during the photomultiplier scoop's blanking interval pulses, so as not to interfere with the scanning.

In the United Kingdom, Rank Precision Industries was[when?] experimenting with the flying-spot scanner (FSS), which inverted the cathode ray tube (CRT) concept of scanning using a television screen. The CRT emits a pixel-sized electron beam which is converted to a photon beam through the phosphors coating the envelope. This dot of light is then focused by a lens onto the film's emulsion, and finally collected by a pickup device. In 1950 the first Rank flying spot monochrome telecine was installed at the BBC's Lime Grove Studios.[7] The advantage of the FSS is that colour analysis is done after scanning, so there can be no registration errors as can be produced by vidicon tubes where scanning is done after colour separation — it also allows simpler dichroics to be used.