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Two Lasers?

B

Bumbler

Junior Member
Why can't we add an extra laser to the existing design for CD/DVD burners? Couldn't we write information to disks twice as fast if we had two lasers?
 
I think DVD Roms have two lasers, im sure some older ones had.

Also, i think it may not work out. For example, If one laser finds a damaged spot on the disk, it would need to write on a different spot but the second laser is having no problems and working smoothly, so instead of working together, one laser might have to stay idle.

Also, two lasers will add more heat and will require more space to work.
 
cd/dvd data is stored in one spiral track, not individual concentric tracks. so one laser would have to write from say the inner edge to the middle, the other from the middle to the outer edge. it would be unfortunate if the 1st lasers data was longer than expected and ran into the 2nd lasers data in the middle for one thing. getting them to meet would be pretty hard as there is no tracking info on a blank cd/dvd (at least for the absolute location, there is a guide grove but it doesnt tell how far into the spiral you are) for the writer to get its bearings on, it would be pure guess work as to where the actual middle is..
 
Originally posted by: CrispyFried
cd/dvd data is stored in one spiral track, not individual concentric tracks. so one laser would have to write from say the inner edge to the middle, the other from the middle to the outer edge. it would be unfortunate if the 1st lasers data was longer than expected and ran into the 2nd lasers data in the middle for one thing. getting them to meet would be pretty hard as there is no tracking info on a blank cd/dvd (at least for the absolute location, there is a guide grove but it doesnt tell how far into the spiral you are) for the writer to get its bearings on, it would be pure guess work as to where the actual middle is..
Click to expand...

True, just imagine one laser has to write 1000 files of various formats and the other is writing a big movie file.
 
Actually there used to be cd-roms with multiple lasers. They were made by Kenwood and pretty much sucked.

http://www.pcmech.com/show/multimedia/178/

Actually it wasn't multiple lasers, just one laser split. Nonetheless, it makes the logic chips more complicated and you have to worry about motors and stepping. Not worth the hassle. Keep it simple.
 
Originally posted by: Codewiz
Actually there used to be cd-roms with multiple lasers. They were made by Kenwood and pretty much sucked.

http://www.pcmech.com/show/multimedia/178/

Actually it wasn't multiple lasers, just one laser split. Nonetheless, it makes the logic chips more complicated and you have to worry about motors and stepping. Not worth the hassle. Keep it simple.
Click to expand...


interesting. but that was only for reading only, not writing.
 
The Kenwood TrueX 72x uses seven laser streams from a single beam and a rotation speed of approximately 10x, but as far as writters go it may have to do with the stream of information coming from the IDE channel and the ability to move and cache the data on the drive itself would be too complex to make the drive cheaply.
 
Originally posted by: CrispyFried
cd/dvd data is stored in one spiral track, not individual concentric tracks. so one laser would have to write from say the inner edge to the middle, the other from the middle to the outer edge. it would be unfortunate if the 1st lasers data was longer than expected and ran into the 2nd lasers data in the middle for one thing. getting them to meet would be pretty hard as there is no tracking info on a blank cd/dvd (at least for the absolute location, there is a guide grove but it doesnt tell how far into the spiral you are) for the writer to get its bearings on, it would be pure guess work as to where the actual middle is..
Click to expand...

Actually I've read a bunch of patents where a tracking pattern was imprinted on the substrate for exactly this purpose.
 
Originally posted by: CrispyFried
Originally posted by: Codewiz
Actually there used to be cd-roms with multiple lasers. They were made by Kenwood and pretty much sucked.

http://www.pcmech.com/show/multimedia/178/

Actually it wasn't multiple lasers, just one laser split. Nonetheless, it makes the logic chips more complicated and you have to worry about motors and stepping. Not worth the hassle. Keep it simple.
Click to expand...


interesting. but that was only for reading only, not writing.
Click to expand...

Yeah and we couldn't even get reading to work 100%.

Now with all the copyright management software crap they put on cds, I bet those drives work evenless now.

 
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