Browse Prior Art Database

Optical Media Combining Reversible and Write-Once Attributes

IP.com Disclosure Number: IPCOM000122792D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Hurst, J: AUTHOR [+3]

Abstract

Disclosed is a magneto-optic media which can be used as a permanent write-once (WORM) media. The invented media consists of reversible magneto-optic media in a quadrilayer structure. The media is optimized for high magneto-optic SNR. The media is used for permanent WORM recording by applying high power laser pulses which are typically twice as high as used for reversible recording, which cause irreversible changes to the magnetic properties of the film. After writing, the magnetic film in the high power irradiated region no longer exhibits significant Kerr rotation. Either before or after writing, it is required to have an erase pass using erase conditions typical for reversible erasing of the magneto-optic media. The data is read back using conventional magneto-optic detection.

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Optical Media Combining Reversible and Write-Once Attributes

      Disclosed is a magneto-optic media which can be used as a
permanent write-once (WORM) media.  The invented media consists of
reversible magneto-optic media in a quadrilayer structure.  The media
is optimized for high magneto-optic SNR.  The media is used for
permanent WORM recording by applying high power laser pulses which
are typically twice as high as used for reversible recording, which
cause irreversible changes to the magnetic properties of the film.
After writing, the magnetic film in the high power irradiated region
no longer exhibits significant Kerr rotation.  Either before or after
writing, it is required to have an erase pass using erase conditions
typical for reversible erasing of the magneto-optic media.  The data
is read back using conventional magneto-optic detection.  The
write-once signal is weaker by a factor of 2 (6db) since the written
domain does not cause a Kerr rotation.  This WORM recording method
was experimentally  demonstrated.  Trailing edge-to-trailing edge
jitter associated with write-one and reversible recording was 2.5ns
and 1.3ns, respectively.

      This WORM media is fully compatible with ROM and reversible MO
data.  Any sector can have any of those properties.  ROM data is
placed in desired regions during the mastering process using the
conventional pit formation process.  Reversible data is written and
erased in the same  fashion as conventional mag...