The blue period of lasers
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| Posted by | Robin van Lieshout |
| Posted on | 27/07/02 20:18 |
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The blue period of lasers
Author: Mr. Belvedere - Date: 27-7-2002
A little science firstAs we all know, CD players and recorders read and write the CD's with the aid of a laser. Laser is short for: Light Amplification by Stimulated Emission of Radiation. See http://www.howstuffworks.com/laser1.htm for a complete explanation of what a laser actually is.
In a nutshell this means that high emitted energy gives radiation in the form of light, sort of like a lightbulb does. However laser light is very different than your average lightbulb. Laser comes in a straight direct beam and in only one wavelength (only red, only green, only blue etc). This wavelength is measured in nanometers and science uses the Greek letter Lamda (
) for this.
See http://www.howstuffworks.com/light2.htm for more information about wavelengths and light.Because a laser is a very tiny and direct beam it is perfect to reflect the data written on a cd, because the data is long (over 3 miles!) but it is very small (about 5 microns).
(Picture courtesy of http://www.howstuffworks.com/cd2.htm)
The laser sends a beam towards the cd data and the beam gets reflected or not, thus resulting in high or low digital signal. To put it simple: If the reflected beam gets picked up by the receptor, it's a 1 ,if not.. it's a 0.
If you write data on a cd, the real laser power kicks in. It actually heats up a certain part of the cdrom surface, thus creating a physical 0 or 1 on the cdrom, which can later be read by your cd player. This will be explained more thoroughly later on (Pages 9 and 10).
The smaller the wavelength of a laser is, the smaller the beam can be. If the beam is smaller .. it can also read/write the same data using a smaller width (less than 1 micron!). So, on the same amount of surface, a laser with a smaller wavelength can read/write far more data on that surface than a laser with a bigger wavelength! And that's what Blu-Ray is! A laser with a smaller wavelength. Blue.
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Posted by nEXusJ on Wednesday 31 July 2002 03:33
Cool post, Mr. Belvedere. 
Great info on the BD. So, when's the expo on the 130GB CD3?
Later,
nEXusJ
Great info on the BD. So, when's the expo on the 130GB CD3?
Later,
nEXusJ
Posted by dansmug on Thursday 01 August 2002 22:30
I thought there were so little reactions, I felt compassion with Mr. Belvedere. So once again: nice article.
Ok. Great article... but... Why are they using MPEG2? We live in a world where MPEG4 has taken over(divx). All they need to do is creat a MPEG4 for super high resolutions(1080p).
Same with audio. By that time we will have DD10.2 or something like it. Audio should be encoded in WMA8(divx audio) or MP3PRO.
Same with audio. By that time we will have DD10.2 or something like it. Audio should be encoded in WMA8(divx audio) or MP3PRO.
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