At 09:30 AM 11/18/2014, Mouse wrote:
I was speculating that, on the scales of interest
here, it's
easier/cheaper to produce a non-smooth surface of a uniform material
(how pressed CDs are actually made) than to produce a smooth surface of
a nonuniform material (the alternative).
I see... you're asking why CDs couldn't be made with a printing process
(ink on paper being effectively smooth) as opposed to the non-smooth
method of pits and lands. On one hand, it almost sounds like you've
re-invented CD-R, where a dye gets zapped and changes its reflectivity -
but I was surprised to read that even CD-Rs have a single spiral
"pre-groove" pressed into the polycarbonate. You'd need a rather precise
printing process to make tiny spots.
Yes, but I think the light normally used for CD
reading is outside the
visible range. This raises the possibility that the disc might be
clear in the visible range but not in the range used for reading. Your
experience trying to read it argues against that, though. Oh well, it
was a nice theory while it lasted.
At this point, I only hold out hope for finding an existing reader that
can see the pits, and the best candidate seems to be the oldest readers,
not the newest.
I can't help but think this is an important topic for data recovery. A
peeled reflective layer is a common failure mode for discs. If there
was a way to dissolve everything above the pits (the label and aluminum)
and recoat with acrylic for protection, and read a clear CD, you could
rescue failed CDs.
Couldn't one also apply a layer of aluminum? This is commonly done with
mirrors for optics in telescopes and such, by hobbyists. I'm not 100%
familiar with the process, but I understand it is done in a small vacuum
chamber with some sort of electrical process to vaporize the aluminum.
I think I actually have a /very/ early Philips cd-writer drive in storage,
but it is behind a couple of large stacks of gear. It has a SCSI interface
and is about the size of a home stereo component.
I /might/ also have a Philips CM-100 on another more accessible shelf, but
it may be a few days or a week before I can have a look and see what I
have. I seem to remember the drive I have has an unusual data connector.
Does the CM-100 require a special interface card?