Information about Flying Spot Scanner
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The parts of a flying spot scanner: (A) Cathode-ray tube (CRT); (B) photon beam; (C) & (D) dichroic mirrors; (E), (F) & (G) red-, green- and blue-sensitive photomultipliers.
A flying-spot scanner (FSS) uses a scanning source of a spot of light, such as a high-resolution, high-light-output, low-persistence Cathode Ray Tube (CRT), to scan an image, usually from motion picture film or a slide. The output of the scanner is usually a television signal.
Basic principle
In the case of the CRT-based scanner, as the electron beam is drawn across the face of the CRT, it creates a scan that has the correct number of lines and aspect ratio for the format of the signal. The image of this scan is focused with a lens onto the film frame. Its light passes through the image being scanned and is converted to a proportional electrical signal by Photomultiplier tube(s), one for each color (Red, Green, Blue) that detect the variations in intensity of the beam spot as it scans across the film, and are converted to proportional electrical signals, on for each of the color channels.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 be no registration errors, as would have been introduced by early electronic cameras.
Early use
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.See also
- Frank Gray (researcher), inventor of (mechanical) flying-spot scanner
References
1. ^ Flying Spot Scanner TV Camera. earlytelevision.org.
2. ^ Knox McIlwain and Charles Earle Dean (1956). Principles of Color Television. Wiley.
2. ^ Knox McIlwain and Charles Earle Dean (1956). Principles of Color Television. Wiley.
External links
- Science Newsletter, April 16, 1927 (reproduced at Science News Online) "How New Television Process Works" with Gray's flying-spot scanner innovation
1. Electron guns 2. Electron beams 3. Focusing coils 4. Deflection coils 5. Anode connection 6. Mask for separating beams for red, green, and blue part of displayed image 7.
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Television (often abbreviated to TV, T.V., or more recently, tv; sometimes called telly, the tube, boob tube, or idiot box in British English) is a widely used telecommunication system for broadcasting and receiving moving pictures
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Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible and near infrared. These detectors multiply the signal produced by incident light by as much as 108
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Telecine (IPA pronunciation: [ˈtɛləˌsɪni] or [ˌtɛləˈsɪni]; [ˌtɛləˈsɪnə]; also [ˌtɛləˈsiːn].
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Frank Gray was a physicist and researcher at Bell Labs who made numerous innovations in television, both mechanical and electronic, and is remembered for the Gray code.
The Gray code, or reflected binary code, appearing in Gray's 1953 patent,[1]
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The Gray code, or reflected binary code, appearing in Gray's 1953 patent,[1]
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