[rollei_list] Re: Rangefinder article
- From: "Peter K." <peterk727@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 15 Jun 2007 14:41:04 -0700
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
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 9:24 AM
Subject: [rollei_list] Re: Rangefinder article
Thanks for the kind words Carlos. Much appreciated.
Saludos,
Peter K
Very good and useful article. I may have missed something
but did you explain how re-writable discs work? My
understanding is that this is a dye image which can be
erased or written over by using UV light.
Is the heat generated image dye or bubbles? If bubbles
its probably more permanent than dye. If its bubbles it
sounds like a variation of the old Kalvar process.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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Peter K
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