Multiple data surface optical medium and storage system with fixed aberration correction
CA 2123450 C · Owner: International Business Machines Corporation · Inventors: Imaino, Wayne I.; Rosen, Hal J.; Rubin, Kurt A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An optical data storage system uses an optical medium made of a stack of spaced-apart optical disks. Each disk in the stack is made of light-transmissive material, such as polycarbonate when the system is a CD-ROM system, and has a partially light-transmissive data layer on at least one of its faces. A focusing lens in the system focuses light to the data layers along optical paths with, each data layer corresponding to a unique optical path length. The light is focused to each data layer by reflection off adjacent data layers such that the total substrate thickness through which the light passes is the same for each optical path. In this manner the fixed spherical aberration correction …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed May 12, 1994 and granted September 15, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 12, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 12, 2016.
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Timeline
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.