Double-Layer DVDs Now Offer—You
Guessed It—Double The Storage Capacity
By Dikla Kadosh
PCPhoto often
recommends to readers that DVDs are ideal for backing up and
archiving your digital photo and video files. They’re also
convenient for sharing your photos because they can be popped
into any computer with a DVD drive or many DVD players and easily
accessed. DVDs are a familiar, easy-to-use medium and are relatively
inexpensive.
A good storage solution
has suddenly become a great storage solution with the advent
of the double-layer DVD, which nearly doubles the capacity of
a recordable disc from 4.7 GB to 8.5 GB. That’s equivalent
to four hours of DVD-quality video, thousands of high-resolution
images and hundreds of thousands of important documents or applications
you want to back up from your computer’s hard drive.
The advanced new format is double-layered, not double-sided,
so you don’t have to flip the disc over during recording.
All the data is stored on one side and when the contents are
viewed as a video, the transition between the layers is practically
seamless. And the best part is that this new media is compatible
with most existing DVD players and DVD-ROM drives, so you don’t
have to buy all new hardware to take advantage of this amazing
technology. It does require a dual-layer burner to record data
onto the DVDs, however.
Two separate coalitions of manufacturers got together to come
up with the double-layer DVD. Each group produced its own version,
with only slight variations in the technology. Both standards,
DVD+R DL and DVD-R DL, feature two thin layers of substrates
that are bonded by a specially designed UV adhesive. When burning
data onto these discs, the laser writes to the first layer,
then increases its power slightly in order to write to the second
layer.
The group that developed the DVD+R DL format incorporated a
thin layer of silver-alloy in the upper layer. This produces
reflectivity that complies with DVD-ROM standards, making the
disc compatible with current players. The laser beam is able
to pass through this reflective layer as well as the first substrate
level and write directly to the second layer. Enhancements such
as increased write and read speeds and rewriteable versions
already are in the works.
In the DVD-R DL format, the reflection film on the first layer
is semi-transparent and the bonding agent is completely transparent.
When the first layer is filled to capacity with data, the laser
automatically moves to the second layer. The two layers are
regarded as a single continuous volume.
Like the multi-gigabyte memory cards now available, these high-capacity
DVDs give you the option of putting a substantial amount of
data in one place. 8.5 GB may seem like more space than you’ll
know what to do with, but with the increasing sizes of high-resolution
photo and video files, you’ll be filling that up and asking
for more before you know it.
A very wise man once said to me, if some is good, and more is
better, than too much should be just right. Although he was
referring to something else entirely, I think the adage also
fits well in the case of storage.
