New Laser Could Support 10x Recording on Dual-Layer Blu-Ray Media

[Gizmo]

Japanese Nichia Corp. has developed a blue-violet semiconductor laser diode, featuring a power high enough for burning Blu-Ray and HD DVD media at high speeds.

Read more on the Front Page:
http://www.aoaforums.com/frontpage/content/view/2039/2/

[Rondog]

Hmm, interesting development, if 10X on BluRay is possible. Then how is DVD limited to 20X. Surely this laser tech can be applied to DVD. Or am I all kinds of wrong?

[noob]

The speed limit for DVD's and CD's has to do with physical media tensile strengths.

CD x1 ~ 500 RPM
DVD x1 ~1500 RPM

CD's have a max sustained rotational speed of ~23,000 RPM (46x)
DVD's have a max sustained rotational speed of ~32,000 RPM (21x)

Because of the new nature of Blu ray / HDDVD, using a blue-violet laser as opposed to a red one, the pits are far closer together. This allows a much faster transfer speed without the initial requirement to speed up the disc.

Also because of certain design aspects (real blue-violet lasers haven't been around long), it has been harder to get similar power outputs as the more established red lasers, even though the shorter wavelengths have a higher intensity. Especially with the miniaturisation required.

As for speed -

Blu ray 1x = ~2000 RPM

assuming same parameters as DVD's 32,000 RPM max sustained = 16x
If they could be made stronger and reach say 40,000 RPM that would be 20x

Data speeds are also different;

CD 1x = 150kB/s
@ 12x (6000 RPM) = 1.8MB/s
@ max 46x = 6.9MB/s

DVD 1x = 1.32MB/s
@ 4x (6000 RPM) = 5.28MB/s
@ max 21x = 27.72MB/s

Blu ray 1x = 4.5MB/s
@ 3x (6000 RPM) = 13.5 MB/s
@ max 16x = 72MB/s
@ max 20x = 90MB/s

NOTE:
Max sustained speeds allow for a margin of safety. Mainly for unbalance to begin with, but now also includes sub standard widely avaliable media.