DVD - Digital Versatile Disk
In 1995, new standard was established for DVD Digital Versatile Disk (called at first Digital
Video Disk). They were first developed for storing a full digital movie.
DVD can store up to
4.7 [
GB]
information on a single layer on the disk.
The new devices can store information on both sides, so the total amount of information is 9.4
[
GB] (!!!).
The size of the DVD is the same as CD, but because it use a shorter wavelength, the pits can
be smaller (minimum size 0.4 [
µ
m]) and so is the distance between tracks (0.74 [
µ
m]).
CD-ROMs are based on Diode laser with Infra-Red wavelength of 780 [nm].
DVD devices are based on Diode laser with red wavelength of 650 [nm].
Blue Diode Lasers and the DVD
When blue Diode laser (
$
= 450 nm) becomes commercially available, the amount of information on
the DVD can increase a few times.
In February 1996 a Japanese company announced the first blue diode laser (
$
= 410 nm), operating
at room temperature.
The predicted amount of information on such disk can be
60 [
GB] !!!
