Apparatus and methods for forming and use with variable pit depth optical recording media
CA 2249403 C · Owner: Calimetrics, Inc. · Inventors: Spielman, Steven R.; Wong, Terrence L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An apparatus (figure 2) and method for forming a digital optical disc master from a disc having a substrate (300) coated with a photoresist coating (320). The method includes irradiating the surface of the photoresist material (320) with a laser beam (310) at a multiplicity of pit locations over the substrate (300) causing the photoresist material (320) to react to the laser radiation (310) to form at least three different discrete levels at the multiplicity of pit locations relative to the surface of the substrate (300) due to the dose of radiation applied being calculated to react with the photoresist to a depth equivalent to the discrete levels. The exposed photoresist is then …
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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 March 24, 1997 and granted January 9, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 24, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 24, 2019.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
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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.