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Newsletter
Still Trouble with FE & TE at High Speeds?
100% Detection for Acceleration Defects from Dr. Schenk
DVD±R is getting more and more common as a storage
medium. Even though they have high storage capacity,
recording speeds, until recently, only reached up to 8x and
even less for dual layer, demanding lots of patience from users.
High demand for faster recording was emerging noticeably.
However, doubling the recording speed from 8x to 16x, for
example, is far from being simple, as the pick-up is forced to
accelerate much more than simply double the speed. Even
slightest deformations on the disc, which can be ignored at 8x,
can cause the pick-up to loose the focus or the track at higher
speeds, leading to Focus Errors (FE) and Tracking Errors (TE).
One Solution for All High Speed Discs
Dr. Schenk is the first to launch a complete solution for highspeed
discs for reliable 100% detection of slightest local deformations,
which lead to acceleration defects (ACC defects).
Acceleration defects play a major role in respect of proper
playability. This solution takes a high-resolution image of each
disc, making acceleration defects optically visible for the very
first time. Now, 100% detection of even the tiniest acceleration
defects for reliable Focus and Tracking Error evaluation can
be realized in-line, incorporated in the production line.
High-resolution measurement of smallest local deformations
is particularly important for high-speed DVD±R and DVD±R
DL discs, demanding maximum flatness for proper recording.
However, the innovative optical concept of this solution makes
it also applicable for any speed, as well as for all upcoming
high density discs, such as HD DVD and Blu-ray Disc.
Available as two options, integrated in the latest ISM in-line
scanner family, as well as in the comprehensive off-line measurement
system PROmeteus MT-200, immediate feedback
on process issues is provided.
Dr. Schenk GmbH • Industriemesstechnik • Einsteinstrasse 37 (Martinsried) • D-82152 Planegg • Germany
Phone: +49-89-85695-0 • Fax: +49-89-85695-200 • www.drschenk.com • info@drschenk.com
Phone Dr. Schenk Worldwide: USA: +1-651-730-4090 • Japan: +81-45-929-6106 • Korea: +82-2-527-1633
Taiwan: +886-2-2920-7899 • Hong Kong: +852-2425-1860 • China: +86-10-6503-2159 • Thailand: +66-2-662-5505
Copyright Dr. Schenk GmbH, 03/2006
Challenges for Disc Replicators
Production sites face big challenges with high-speed disc
production. Conventional in-line inspection equipment only
successfully inspects DVD±R discs up to 8x, so that slightest
local deformations, critical for faster speeds, remain undetected.
Replicators are urged to test each single high speed disc on
separate commercial drives after production. However, not
only that the testing time is quite long, but also only the outer
ranges of the discs are tested. Without doubt, most focus
errors appear at the outer ranges, but FE and TE defects can
also occur anywhere else on the disc.
To overcome the extremely long cycle times, several drives
are applied in parallel, resulting in huge additional costs for
the test equipment itself, much required space, as well as
handling time. During this extra treatment, additional damage
can easily happen to the discs. Moreover, commercial drives
are only laid out for one specific disc format, requiring the
provision of multiple different drives for the various disc formats
produced.
Commercial drives only provide a single value for each FE and
TE as results of the tested discs, making process optimization
extremely difficult. Overall, these drives are not laid out for
testing FE and TE defects. Therefore, repeatability and correlation
tests are everything other than reliable.
Who can afford exploding production cycle times and huge
costs in an industry, where everybody eagerly attempts to
shorten cycle time and optimize production?
The Unique Solution from Dr. Schenk
March 2006
For reliable quality assurance and efficient process control,
every single high-speed disc must be fully measured and
evaluated in-line and, of course, preferably with no influence
on the disc cycle time.
In the course of continuous enhancements of the already proven
ACC channel for up to 8x, Dr. Schenk has come up with the
optimum solution for acceleration defect detection on more
demanding discs. The new option is called Enhanced ACC
Channel and is able to make even the slightest acceleration
defects visible, which otherwise could lead to focus errors or
focus and tracking errors.

Newsletter March 2006
Fig.1a) ISM with Standard Acceleration Defect Channel
Fig.1b) ISM with ENHANCED ACC Channel making slightest
local deformations visible!
Conventional solutions only test selected radii, allowing acceleration
defects, located between the tested tracks, to remain
undetected. The Enhanced ACC Channel delivers incomparably
much more than a simple good/bad decision. It tests
the complete data area of each single disc with no exception,
providing detailed information on the defect type and size with
its exact position and together with a significant high-resolution
gray image. Despite the large measurement area, there is no
influence on the cycle time, as the test takes place simultaneously
during general disc inspection.
The Enhanced ACC Channel option is fully integrated into the
ISM in-line scanners. Now, for the first time, real-time process
feedback enables replicators to optimize the production process
based on acceleration defects. In addition, each type of local
deformation points to the associated process step, causing
that defect, e.g. a dimple indicates a problem during the bonding
process for DVD±R DL discs. The yield for high-speed discs
can be drastically enhanced by process issues being reported
and pinpointed immediately as they occur - on the straightforward
user interface or, optionally, by an acoustic signal.
No Acceleration Defect Remains Undetected!
An ideal complement to the indispensable in-line solution is
achieved by the HIGH-RES ACC option of the comprehensive
off-line measurement system PROmeteus MT-200. This
valuable option enables high-resolution measurement of local
deformations on the complete disc in just approx. 30 seconds!
a) b)
Fig.2) The disc map, showing local deformations, taken with
the MT-200 (a) optimally correlates with the ACC map
of Electrical Test Drives (b)
Compared to the in-line solution, the MT-200 provides far more
analytical tools for detailed analysis of the measured defect
information. The results can be displayed in multiple views,
e.g. as an accurate disc map with all details.
The HIGH-RES ACC option complements reliable process
control for the challenging high-speed disc production.
How was this Innovative Solution Achieved?
A sole software solution, if it were at all possible, would absorb
enormous computing time. The unique options from Dr. Schenk,
however, are based on the perfect synergy between an innovative
hardware solution and a specially developed algorithm.
This makes it possible to achieve results, which correlate
optimally with the FE and TE results of pick-up drives.
Fig.3) The Focus Error signals of Electrical Test Drives (a)
also optimally correlate with the signals of the
Enhanced ACC Channel of the ISM (b) and the HIGH-
RES ACC of the MT-200 (c).
These new options measure the acceleration topography of
the complete disc surface, which a pick-up head has to follow.
As result, the ISM in-line scanner delivers a detailed highresolution
gray image and the PROmeteus MT-200 optionally
delivers a gray image or a false color map in a 3-D picture.
Avoiding the use of mechanical pick-up heads, these optical
measurements can virtually be carried out at any speed, making
them applicable not only for today’s high-speed discs, but also
for the upcoming high density discs, like HD DVD and Blu-ray.
Proven in Mass Production
Developed in close cooperation with technology leaders, the
comprehensive in-line and off-line solution from Dr. Schenk is
already fully established and successfully running at leading
disc production sites. Those replicators noticeably improved
their production process, as well as their yield within a very
short period of time. Replicators will highly appreciate these
indispensable new options, resulting in increasingly profitable
high speed disc production.
Dr. Schenk GmbH • Industriemesstechnik • Einsteinstrasse 37 (Martinsried) • D-82152 Planegg • Germany
Phone: +49-89-85695-0 • Fax: +49-89-85695-200 • www.drschenk.com • info@drschenk.com
Phone Dr. Schenk Worldwide: USA: +1-651-730-4090 • Japan: +81-45-929-6106 • Korea: +82-2-527-1633
Taiwan: +886-2-2920-7899 • Hong Kong: +852-2425-1860 • China: +86-10-6503-2159 • Thailand: +66-2-662-5505