[rollei_list] Re: Rangefinder article

  • From: "Peter K." <peterk727@xxxxxxxxx>
  • To: rollei_list@xxxxxxxxxxxxx
  • Date: Fri, 15 Jun 2007 17:52:50 -0700

Yes Richard, documents that are not easily found or rare should be
kept on something more archival like a DVD+R. They will outlast CDs.
Also burn them at a slower rate to ensure best burn and longer
readability. A slower burn ensure more accurate shaped pits/markings
resulting in a potentially longer archival/readability.

Peter K

On 6/15/07, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:

----- Original Message -----
From: "Peter K." <peterk727@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Friday, June 15, 2007 2:41 PM
Subject: [rollei_list] Re: Rangefinder article


Hi Richard,

Thank you. The RW disks actually require the laser to
erase/blank them
before they are written. They usually use a material
different than
dye so that they can control the phase change. The material
is
basically one where a higher power laser and subsequent
cooling
changes the state of the material used. To erase the
pits/disk in a
disk, or blank it, there is a process known as annealing
accomplished
by heating the material to a lower temperature.

Problem with RW is that although the claim is that they will
last a
long time, they do not meet the higher standards of write
once
CD/DVDs. While you might use them for storing images for a
few months,
DVD-R/+Rs are less expensive and offer more stable long-term
storage,
it only makes sense to stick with those if you are
archiving.

UC Berkeley has a good article (from 2001) posted that
offers a better
detailed explanation of the RW process at:
http://www.mse.berkeley.edu/classes/matsci102/F01reports/dvdrw.pdf

Peter K

   Thanks Peter, I will check out the reference. I use discs
mainly for storing documents. I expect reasonable life,
several years minimum, but not archival life. It sounds like
I should copy the more important stuff to write-once discs.
   FWIW, there appears to be an astonishing amount of
technical publications of historican importance on the web.
For instance, I recently downloaded two RCA internal
publications with all their proprietary knowledge about
designing and making vacuum tubes. This is simply not
available elsewhere.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx

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Peter K
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