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Browse Prior Art Database

Testing Reliability Margins in Optical Storage Devices

IP.com Disclosure Number: IPCOM000110586D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Engler, EM: AUTHOR [+5]

Abstract

A special diagnostic optical test disk is described which simulates the effect of read signal loss and write power loss due to contamination or other degradation mechanisms in optical storage devices. Coating a standard optical disk reduces reflectivity and permits testing of the drive's recording margins. Varying levels of reflectivity are obtained by changing the thickness of the coating. Silicon carbide, as well as other materials, are useful in providing sufficient reflectivity changes. Silicon carbide, in particular, is well suited for coating a disk to avoid heat damage to the disk from RF sputtering, disk surface reactions from reactive gas sputtering, or requirements that a disk coating be electrically conductive for DC magnetron sputtering.

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Testing Reliability Margins in Optical Storage Devices

       A special diagnostic optical test disk is described which
simulates the effect of read signal loss and write power loss due to
contamination or other degradation mechanisms in optical storage
devices.  Coating a standard optical disk reduces reflectivity and
permits testing of the drive's recording margins.  Varying levels of
reflectivity are obtained by changing the thickness of the coating.
Silicon carbide, as well as other materials, are useful in providing
sufficient reflectivity changes.  Silicon carbide, in particular, is
well suited for coating a disk to avoid heat damage to the disk from
RF sputtering, disk surface reactions from reactive gas sputtering,
or requirements that a disk coating be electrically conductive for DC
magnetron sputtering.  Sputtering process parameters are optimized
for appropriate optical properties, such as the indices of refraction
and absorptivity, and mechanical properties such as stress.  Either
multiple disk with different reflectivities or a single disk with
bands of varying reflectivity can be used to determine what signal
level reduction causes read/write problems.  Use of these diagnostic
disks can differentiate between different drive designs and guide in
the development of robust systems that maintain performance even
after considerable degradation.  From the user's perspective, an
indication of the error margins in a drive can be valuable in
maintaining opt...