Double laser header is more reliable?

[m.rock.shell]

help!

[cfitz]

Be more specific. What exactly is your question? Most modern DVD-ROM drives use a dual laser pickup with one laser tuned to read CDs and one tuned to read DVDs. That gives the drive good multi-format capability.

cfitz

[Raz0rX]

I have once opened up a Liteon 16x DVDROM and it only has one laser head. The laser head has two lenses for reading diff. wavelegth.

[cfitz]

From the Lite-On FAQ's:

Q10 Why DVD need dual wavelength laser pick-up head(PUH)?
A10 Due to small pit and track pitches, DVD media only can be read by laser at 680nm wavelength. However, due the reflexibility issue of the CDR dye material, laser at this wavelength can NOT read CDR media. So, to satisfy the compatibility of DVD-ROM drives, dual-frequency PUH is used to read most CD-ROM/CDR/CDRW media available. In the earlier years, people have developed dual lens PUH to solve this problem, but this design is NOT successful due to the extra costs.

( http://www.jlms.com.tw/faqs.htm#dvd-rom_10 )

By the way, Raz0rX, when and under what circumstances did you become a CD-RW Curmudgeon? I thought I was the only one...

cfitz

[Raz0rX]

I have read on Samsung's site awhile ago that they acutally implement dual-lense on a single laser head, Annular Mask Lens. It is used in Samsung 16x DVDROM and many more.

Hmm, don't realize my status until you mentioned it

[cfitz]

The single laser head may well have two laser diodes in it to produce the two wavelengths. In my original post I wasn't implying that two completely distinct laser assemblies would be included in the drive. Rather, I meant two laser diodes in one PUH assembly. It wouldn't surprise me that even with two laser diodes, two lenses are used because the focus point of a lens shifts with wavelength.

I got my "Curmudgeon" status because I was being too grumpy:

http://www.cdrlabs.com/phpBB/viewtopic.php?t=7671

Maybe yours is a mistake, since I haven't noticed you being irritable.

By the way, as I type this I have WinAmp up and running, listening to some great mixes from http://www.djdoboy.com . I take it you are dj doboy? Anyway, I wanted to say I am enjoying the mixes.

cfitz

[Raz0rX]

Thank you for correcting me about the laser head lesson. I was not brave enough to rip off the lense since I don't have the proper equipment anyway to protect myself.

Good to hear that you like his mixes, I am not DJ Doboy but I help to spread out his name/works. I am a big trance lover and he's one of my fav. DJs.

My status, of course, it's a mistake

[cfitz]

Good to hear that you like his mixes, I am not DJ Doboy but I help to spread out his name/works. I am a big trance lover and he's one of my fav. DJs.

Well, good job spreading the word. He has one more fan now.

My status, of course, it's a mistake

And being a trance lover, I suspect you aren't old enough to qualify as a curmudgeon anyway...

Hey Ian, Dan, Socheat, or whoever the mystery "curmudgeon deemer" is, how about restoring Raz0rX's status so he isn't tarred with the same brush reserved for irritable, grumpy old me?

cfitz

[Raz0rX]

I PMed Ian