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Integrated Optical Storage Medium and Substrate

IP.com Disclosure Number: IPCOM000112683D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Moylan, CR: AUTHOR

Abstract

Magneto-optical storage media and the preferred optical storage substrates (polycarbonate and amorphous polyolefin) are incompatible to a large extent. These substrate materials are chosen based on their optical transparencies and physical stiffness, and are not easily replaced by other materials. As porous polymers, they permit the diffusion of oxygen and water vapor from the environment to the chemically sensitive metallic media layer. Due to the mechanism of magneto-optical storage, any birefringence that develops over time is deleterious to disk performance.

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Integrated Optical Storage Medium and Substrate

      Magneto-optical storage media and the preferred optical storage
substrates (polycarbonate and amorphous polyolefin) are incompatible
to a large extent.  These substrate materials are chosen based on
their optical transparencies and physical stiffness, and are not
easily replaced by other materials.  As porous polymers, they permit
the diffusion of oxygen and water vapor from the environment to the
chemically sensitive metallic media layer.  Due to the mechanism of
magneto-optical storage, any birefringence that develops over time is
deleterious to disk performance.

      The approach described here is to use organic media and combine
them with the polymers that are being used for optical substrates.
Writing and erasing can thus be accomplished by focusing a beam onto
the disk at any depth desired.  Reading could be accomplished with
great sensitivity by measuring the difference in transmitted laser
intensity between the domain in question and a blank portion of the
disk.  Birefringence would not affect the storage process, since
optical rotation would not be measured for reading purposes.
Compatibility problems between the storage medium and the substrate
disappear because they are the same material.

      Reversible photochemistry was demonstrated in four materials,
each consisting of a photochromic fulgide compound dispersed in a
matrix of either polycarbonate or polyolefin.  The first fulgide,
available from Aldrich, was
trans-2-{1-(2,5-dimethyl-3-furanyl)ethylidene}-3-
(1-methylethylidene)succinic anhydride.  The second, available from
Aberchromics, Ltd., is called Aberchrome 670 and is an adamantyl
derivative of the first.  Polycarbonate was o...