The blue period of lasers
detail information
| Posted by | Robin van Lieshout |
| Posted on | 27/07/02 20:18 |
Menu
The recording technologyBasically you have two version of recording:
- One time recording : making permanent changes to a disc
- Record many times : the ability to change a disc many times
If you use a CD-RW (record many times) the material on the disc itself changes, but can be changed back again. You can do this as long as the material doesn't get worn out. After about a 1000 times the material does not change back to another state anymore. The materials used to make such a rewritable method possible are special crystals that can go back to their original state.
By heating up the crystals, they change form. Now when you quickly cool them. they stay in that form (which is different from its original form). This is called the amorphous state of the crystals. They have changed form and it stays that way. Your cd player can read it (although it has a little less reflection than cd-r's, it has no problems with it).
Now, if we want to erase the CD-RW , we have to make sure that we lose all the data. So we want to get rid of the amorphous state. By heating up the material again, but this time using more time and less heat, the material gradually wants to take back its old form again , and thus the info is erased. This state is called the (poly)crystalline state.
So, by very quickly heating it and very quickly cool it, we can give the crystals another state (the amorhphous state) which thus contains data and by quite slowly heating it and quite slowly cool it, we can give the crystals their old form back (the crystalline state) which contains no more data. It's a constant change of phases. And so they called it phase change recording.
(Picuture courtesy of Pioneer)
Get RID of itWant to submit your own review? Click here
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.
Related tags
A tag is a relevant keyword or term associated with or assigned to a piece of information (like picture, product, or video clip), thus describing the item and enabling keyword-based classification of information it is applied to. We use it to make searching our database easier and enable all our users to contribute to our database.
add a tag
Add related tags
Related reviews/articles
Get the latest reviews via RSS 
