Originally posted by twhitehead
It is probably not possible, but I was thinking of vertical data density similar to the current horizontal density, so a 1 cm thick disk could store something like 1000 times what a current disk does (and read maybe 100 times faster, as it would mostly be the laser refocusing, not the disk moving.)
Also an optical drives speed limit is largely due to t to backup my whole hard disk occasionally, but DVD just doesn't have the capacity to do that.
Aren't you thinking 1 mm thick disk? 1 cm is like a half inch. Also, what would you gain duplicating the technology with optical components vs magnetic components? The track finding system would be identical, there would have to be a mechanism for swinging a laser reflector back and forth, it would even be more complicated because it would have to have several reflective surfaces to guide a laser beam back and forth to it's laser/detector.
The way it is done in a DVD or any other optical drive is for the whole lens assembly to drive back and forth radially from center to edge of the media. It would be very difficult to greatly increase the speed of changing tracks like in a HD, which uses a very light swing arm and can go thousands of swings per second. Try that with a blu ray. Besides, the whole laser and lens assembly has to be on the spiral drive assembly. They would have to completely redesign that portion of a drive to make it as fast as a magnetic drive.
They would by definition, to lower the mass of the moving parts, to get the lens and laser off the actual spiral or swing mechanism, mirrors or some such to guide the light back to lasers and detectors.
Maybe they could (are actually) developing nanosized lasers and detectors to be on the swing arm mechanism. One other problem I see with a swing arm mechanism like in a magnetic drive, if the storage media depended on phase relationships with the laser, the phase angle would shift from inner to outer track, further complicating the optical path.
At least with magnetics, there is one head to both read and write in the same unit and they are getting so small as to be almost invisible to the naked eye and so a very small mass so a swing arm can go thousands of excursions per second.
I don't see any advantage of duplicating a magnetic HD with optical components. They are already at 2 terabytes for a 3.5 inch drive and 500 gigs for a 2.5 inch laptop drive.
The other technologies like flash drives have a limit as to the number of write and read cycles, maybe 100,000 such cycles and the unit is mostly dead or beyond the capability of error correcting codes to fix. I think they don't correct more than 2 bad bits in a single byte right now and they could up that to 3 or 4 dead bits at the cost of making longer byte strings but then you start defeating the purpose of the greater capacity of the drives.