The blue period of lasers
detail information
| Posted by | Robin van Lieshout |
| Posted on | 27/07/02 20:18 |
Menu
Blue?Blu-Ray uses a blue laser. Because it uses a blue laser it can store enormous more amounts of data on it than was ever possible using red laser on the same amount of surface (being a 120 mm disc).
To have an even greater precision and make sure every part of the laserlight actually gets hit on the part that is needed for writing/reading the disc, a special lens is used in every cd player.
(Picture courtesy of http://www.howstuffworks.com/cd2.htm)
As perfect as your cd may be the surface is never 100% flat. So it constantly needs to focus to get the information out (Example: You will need binoculars if you want to read the license plate of a car, if that car is at a 10 mile distance of yourself). And even IF the surface was 100% flat, the disc spins. And it spins quite fast! So it can even move up and down a little bit (vibrations) (To follow our example: You will need to refocus your binoculars for that license plate if the car moves away from you or gets closer to you constantly, while you are experiencing an earthquake).
The light gathering capacity of the lens is measured in 'Numerical Apertures" or NA for short. The bigger NA (which means the lens can gather more light), the better.
It also tells about power and refraction, but we won't go into that. If you want more information about the NA formulas and methods see: http://www.gonda.ucla.edu/bri_core/na.htm or http://www.microscopyu.com/articles/formulas/formulasna.html
A little science firstWant 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 
