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LaserDisc

Laserdisc (AKA VideoDisc) technology is a truly fascinating look at what could have been. The technology looks like a larger CD but unlink a CD is recorded using frequency modulation (still via pits and lands like on the CD). This means that the disc is recorded as an analogue signal, where as a CD is a truly digital signal (binary). On top of this, Laserdisc was really a fantastic quality for the time and provided many benefits over VHS such as pausing (with a clear picture) and track skipping. The first optical video disc was invented by David Paul Gregg in 1958. His invention was created on a translucent media and was not sold to consumers, instead he patented it in 1961 and then again in 1969 shortly after which he decided to sell the patents to the Phillips company. Phillips was already working on a system and with the introduction of Gregg’s patents was able to make significant progress. Their goal was to market movies on the discs to consumers so they teamed up with MCA. The first demonstration of the technology with Phillips and MCA was done in 1972 and was subsequently released to consumers in Atlanta Georgia on Dec 15, 1978 (2). This first laserdisc player, the Magnavox VH-8000 retailed for $749 (3). The first movie released on Laserdisc was Jaws and the last two titles to be released was Paramount’s Sleepy Hollow and Bringing out the Dead in 2000.  Pioneer would purchase the format from Phillips in 1980 and continue to produce players until 2009 (see my repair post on my Pioneer CLD-V190). Cnet reported the death of Laserdisc to be January 16 2009, however discs can still be purchased today(1).   How do they work? Laserdisc players utilized Helium Neon Laser tubes as the laser up until 1980, at which point diode laser became more popular (1). See my post on HeNe lasers, but the big downside of these laser is that they run on very high voltages and are very fragile. As time went on the mechanics became more advanced. This lead to the use of laser stabilization for rough discs or external vibration sources and the ability to play LD, CDs and DVDs as well as transitioning form top loading to front loading. The image below shows the method of encoding the video data from the pits and lands. Image By Metazoaire – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=56632014     Sources: 1: http://cultureandcommunication.org/deadmedia/index.php/Laserdisc 2:https://www.historyofinformation.com/detail.php?entryid=3616 3:https://www.computerhistory.org/storageengine/optical-laser-disc-player-is-demonstrated/

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Pioneer CLD-V190 (Repair)

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