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TeknologikL is a place for conversation and discussion about new technologies emerging in consumer electronics with a focus on high-definition video and audio. The blog will cover topics including home theater equipment, digital distribution, media streaming, electronic product reviews and more.

The blog's owners are constantly searching for the next device to satisfy their ever growing hunger for technology. Media junkies standing on the edge of reality, ready to take the jump.

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Evolution of the Optical Disc

Posted July 08, 2008 12:00 AM by Kaplin

Optical discs are one of the most popular methods of storing data electronically on mediums such as Compact Disc (CD), Digital Versatile Disc (DVD), and Blu-ray Disc (BD) among other formats. These discs are written to and read by a laser inside the disc player. When the laser is writing or burning the disc, it creates little pits and bumps on the surface. These pits and bumps are later read by a laser in the disc player, which is translated into the stored data.

Rise of the Optical Disc
The first digital optical disc was created by James T. Russell in 1965. Like many others in that day, Russell wasn't happy with the sound quality of vinyl records. He had an idea for a new type of audio system where there was no physical contact between the disc and the player. The best way Russell found to achieve this was through the use of light. By using a laser to burn light and dark marks on the disc for "on" and "off" positions, he was able to store the data as binary code which uses only 1s and 0s. James Russell is credited for inventing the compact disc. Although the CD is known as the first successful optical disc, it wasn't the first.

The first commercial optical disc format was actually the Laserdisc, which got its name from the laser used in the player. The main difference between Laserdisc and current optical disc technologies is that Laserdisc is the only optical disc format that stores an analog signal. Although Laserdisc was a higher quality than VHS, two factors prevented Laserdisc from becoming as popular.

First Generation Optical Discs
The first and biggest limiting factor of LaserDisc is that the analog signal made it virtually impossible for consumers to create their own discs, due to the way the analog discs had to be written. The other limiting feature of Laserdisc was the higher price compared to VHS tapes. In the end, consumers chose price and ease of use over higher quality.

First generation optical discs such as CD, DVD and the short lived Mini-disc are read using an infrared laser. CD and MiniDisc both use a 780nm laser diode, while DVD uses a laser with a shorter wavelength of 650nm. Once optical disc technology hit the marketplace and people were able to burn their own CDs and then DVDs, it quickly overtook magnetic storage as the leader in portable data mediums. Magnetic storage devices such as the floppy discs and later the zip disc were popular and relatively cheap, but the storage capacity couldn't keep up with optical discs.

Optical Discs Today
The 2nd generation of optical discs includes Blu-ray Disc and the now defunct HD DVD. These discs use a blue laser instead of a red laser to read and write data. By using a blue laser with a shorter wavelength, the data can be written closer together packing more information into the same area. That is why a Blu-ray disc can hold 25GB in the same space a DVD can hold 4.7GB.

Although shortening the wavelength has been a great method to increase optical disc capacity, there have been other improvements as well. Newer lasers are capable of storing data on a separate physical layer that is "stacked" on top of the other. Dual-layer DVDs can hold 9GB of data instead of 4.7 held on regular DVDs. Blu-ray discs also come in single and dual layer varieties of 25GB and 50GB. No one is stopping at 2 layers though; Pioneer has recently demoed a 16 layer Blu-ray disc capable of holding 400GB. The problem with multilayer discs is they are prone to errors, and have a lower yield rate in mass production. This means more "bad discs" come out of the batch.

As can be expected, engineers are continuing their work to improve optical disc technology with many formats and methods vying for the next crown. Some future developments currently being worked on include multi-layered discs, holographic discs, and photonic jets among other technologies.

How CD Burners Work
James T. Rusell - The Digital Compact Disc

Pioneer 16-Layer Blu-ray Disc Features 400GB


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Technical Fields - Education - Seasoned Vet in the Classroom United States - Member -

Join Date: Jul 2008
Location: Troy, NY
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Good Answers: 19

Re: Evolution of the Optical Disc

07/09/2008 10:56 AM

A fascinating look back at the history or optical media. Even as Blu-Ray continues to expand, and talk about depth with 16 layer editions, I wonder if this media has jumped the shark, already.

As bandwidth and server capabilities continue to expand, can digitized media look to move from an actual physical source into total cyberspace?

400GB of information for commercial usage is impressive, especially from one disc. That means no more carrying binders full of CD's or even DVD's to get what you need whenever you need it (or at least a much slimmer binder). But for the recreational user, several questions come into the forefront:

  1. How much does size matter?
    • Does it really become necessary to have all of your personal stock of movies on just a few discs? 400 GB = 40 movies per disc (guesstimate)
  2. How much higher can HD really develop until it is beyond the optic capabilities of the human eye for the general public?
    • Right now, many baby boomers already cannot tell the difference between HD and regular definition, and if the highly publicized mosquito ring tone is of any indication, the range of the human ear decreases at an equal (if not swifter) rate. That means that at some point, this must come to an end because cost of R & D will not be able to keep pace with what people are willing to spend if they cannot REALLY tell the difference from lower definition editions to begin with.

It makes me think of Arthur C. Clarke's 3001: A Final Odyssey:

The main character of the tale was rescued from space after floating in an essentially cryogenic freeze for roughly 1000 years. Once he was resuscitated, this "savage" attempted to come to terms with a millennium's worth of evolutionary and technological advancements. The most interesting part of the opening of the novel for me was Clarke's projections of computer memory development. One of the scientists, who has been given the task of easing the main character back into society, explains that there had not been significant increases in computer memory size in hundreds of years. The reason why this was the case was that eventually memory had been increased in size to the point that it could hold more information than any human could access in a lifetime, even if they sat in front of an interface every hour of every day of his or her life. At that point, researchers started to see that much growth beyond this point was somewhat worthless.

While I don't think it is quite that simple, I think it is also telling that the world wide web, just part of the internet itself, has now grown so large and is filled with so much information that multi-billion dollar companies exist just to help people sort through the information to find what is useful, practical, and hopefully accurate. Will their come a time when there is too much? Most mediaphiles/technophiles (including myself) would say no, but it does make you wonder.

StE - "For 'tis the sport to have the enginer/Hoist with his own petard" -Hamlet Act III, scene 4, 202–209
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