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. Crt-telecine.svg
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 the image to be scanned is on photographic film, such as motion picture film, or a slide or photographic plate. The output of the scanner is usually a television signal.

Contents

Basic principle

In the case of the CRT-based scanner, as an 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 detects the variations in intensity of the beam spot as it scans across the film, and are converted to proportional electrical signals, one 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 no registration errors, as would have been introduced by early electronic cameras.

Early use

The first image of the far side of the Moon, transmitted back to Earth using a flying-spot scanner by Luna 3 in 1959 Luna 3 moon.jpg
The first image of the far side of the Moon, transmitted back to Earth using a flying-spot scanner by Luna 3 in 1959
The U.S. Census Bureau used a flying spot scanner called FOSDIC to digitize census forms stored on microfilm in the 1960s. Film Optical Sensing Device for Input to Computers (FOSDIC).jpg
The U.S. Census Bureau used a flying spot scanner called FOSDIC to digitize census forms stored on microfilm in the 1960s.

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 Nipkow 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.

DuMont Vitascan

Flying-spot scanner technology was later implemented by DuMont Laboratories in the 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.

Broadcast use

Flying-spot scanners were used to scan both still print sides and motion picture film for both broadcast TV and later Post-production use. Flying-spot slide scanners were used for Station identification picture and to turn Test film into test TV pictures. There would be a slide changer like on slide projectors to change the slide. [3] Flying-spot Motion picture film scanners were used since the early days of TV. Since film cameras had better quality than early TV cameras. Early manufactures of Flying-spot scanners were Bosch Fernseh and Cintel. Cintel made Flying-spot scanners from the 1950s until the 2000s. [4] [5] [6] The flying-spot scanner tube had limit life span and quantity decease with use. Most flying-spot scanners use a green light that is shone through the exposed film image into a lens. White light gives a better picture. Flying-spot scanners were replaced with charge-coupled device Line Array – CCD for imaging and a white light to the film. [7]

Flying-spot scanner by Rank Cintel the Mark 3, 1975 Tk-mk-3-rank.JPG
Flying-spot scanner by Rank Cintel the Mark 3, 1975

See also

Related Research Articles

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Telecine is the process of transferring film into video and is performed in a color suite. The term is also used to refer to the equipment used in the post-production process. Telecine enables a motion picture, captured originally on film stock, to be viewed with standard video equipment, such as television sets, video cassette recorders (VCR), DVD, Blu-ray Disc or computers. Initially, this allowed television broadcasters to produce programmes using film, usually 16mm stock, but transmit them in the same format, and quality, as other forms of television production. Furthermore, telecine allows film producers, television producers and film distributors working in the film industry to release their productions on video and allows producers to use video production equipment to complete their filmmaking projects. Within the film industry, it is also referred to as a TK, because TC is already used to designate timecode. Motion picture film scanners are similar to telecines.

Photomultiplier tube Fast, high sensitivty, low noise electronic photon detector

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Film recorder Device that copies content from a computer system to film stock

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Mechanical television

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Sensitometry

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Intermediate film system

The intermediate film system was a television process in which motion picture film was processed almost immediately after it was exposed in a camera, then scanned by a television scanner, and transmitted over the air. This system was used principally in Britain and Germany where television cameras were not sensitive enough to use reflected light, but could transmit a suitable image when a bright light was shown through motion picture film directly into the camera lens. John Logie Baird began developing the process in 1932, borrowing the idea of Georg Oskar Schubert from his licensees in Germany, where it was demonstrated by Fernseh AG in 1932 and used for broadcasting in 1934. The BBC used Baird's version of the process during the first three months of its then-"high-definition" television service from November 1936 through January 1937, and German television used it during broadcasts of the 1936 Summer Olympics. In both cases, intermediate film cameras alternated with newly introduced direct television cameras.

Motion picture film scanner Device that copies content from film stock to a computer system for restoration, sharing over the internet and/or storage

A motion picture film scanner is a device used in digital filmmaking to scan original film for storage as high-resolution digital intermediate files.

Cintel

Cintel was a British digital cinema company founded in 1927 by John Logie Baird and based in Ware, Hertfordshire. The early company was called Cinema Television Ltd. Cinema Television was sold to J Arthur Rank Organization renamed Rank Cintel in 1958. It specialized in the design and manufacture of professional post-production equipment, for transcribing film into video or data formats. It was formerly part of the Rank Organisation. Along with a line of telecines, Rank Cintel made 3 tube RGB color video projectors in the 1960s.

The Fernseh AG television company was registered in Berlin on July 3, 1929, by John Logie Baird, Robert Bosch, Zeiss Ikon and D.S. Loewe as partners. John Baird owned Baird Television Ltd. in London, Zeiss Ikon was a camera company in Dresden, D.S. Loewe owned a company in Berlin and Robert Bosch owned a company, Robert Bosch GmbH, in Stuttgart. with an initial capital of 100,000 Reichsmark. Fernseh AG did research and manufacturing of television equipment.

Film chain

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Vitascan was an early color television camera system developed by American television equipment manufacturer DuMont Laboratories. Development began in 1949 and the product was released on an experimental basis in 1956. Vitascan was fully compatible with the NTSC color system, and DuMont Labs hoped the system would catch on in the television industry.

The technology of television has evolved since its early days using a mechanical system invented by Paul Gottlieb Nipkow in 1884. Every television system works on the scanning principle first implemented in the rotating disk scanner of Nipkow. This turns a two-dimensional image into a time series of signals that represent the brightness and color of each resolvable element of the picture. By repeating a two-dimensional image quickly enough, the impression of motion can be transmitted as well. For the receiving apparatus to reconstruct the image, synchronization information is included in the signal to allow proper placement of each line within the image and to identify when a complete image has been transmitted and a new image is to follow.

Spirit DataCine Motion picture film scanner

Spirit DataCine is a telecine and a motion picture film scanner. This device is able to transfer 16mm and 35mm motion picture film to NTSC or PAL television standards or one of many High-definition television standards. With the data transfer option a Spirit DataCine can output DPX data files. The image pick up device is a solid state charge-coupled device. This eliminated the need for glass vacuum tube CRTs used on older telecines. The units can transfer negative film, primetime, intermediate film and print film, stock. One option is a Super 8 gate for the transfer of Super 8 mm film. With a sound pick up option, optical 16mm and 35mm sound can be reproduced, also 16mm magnetic strip sound. The unit can operate stand alone or be controlled by a scene by scene color corrector. Ken Burns created The Civil War, a short documentary film included in the DVD release, on how he used the Spirit DataCine to transfer and remaster this film. The operator of the unit is called a Colorist or Colorist Assistant. The Spirit DataCine has become the standard for high-end real-time film transfer and scanning. Over 370 units are used in post production facilities around the world. Most current film productions are transferred on Spirit DataCines for Television, Digital television, Cable television, Satellite television, Direct-to-video, DVD, Blu-ray Disc, pay-per-view, In-flight entertainment, Stock footage, Dailies, Film preservation, digital intermediate and digital cinema. The Spirit DataCine is made by DFT Digital Film Technology GmbH in Darmstadt, Germany.

Electrically operated display devices have developed from electromechanical systems for display of text, up to all-electronic devices capable of full-motion 3D color graphic displays. Electromagnetic devices, using a solenoid coil to control a visible flag or flap, were the earliest type, and were used for text displays such as stock market prices and arrival/departure display times. The cathode ray tube was the workhorse of text and video display technology for several decades until being displaced by plasma, liquid crystal (LCD), and solid-state devices such as thin-film transistors (TFTs), LEDs and OLEDs. With the advent of metal-oxide-semiconductor field-effect transistors (MOSFETs), integrated circuit (IC) chips, microprocessors, and microelectronic devices, many more individual picture elements ("pixels") could be incorporated into one display device, allowing graphic displays and video.

References

  1. "Flying Spot Scanner TV Camera". earlytelevision.org.
  2. Knox McIlwain and Charles Earle Dean (1956). Principles of Color Television. Wiley.
  3. radiomuseum.org, Slide scanner
  4. NASA, Visual simulation image generation using a flying-spot scanner
  5. earlytelevision.org, cathode ray tube Rank Cintel
  6. Bosch Fernseh, radiomuseum.org, Flying-spot scanner, 1967
  7. Lees, Roger; et al. (October 1990). "High Performance CCD Telecine for HDTV". SMPTE Journal. 99 (10): 837–843. doi:10.5594/J00101.