Ophthalmic lenses for correcting astigmatism using diffractive patterns
CA 2006016 C · Owner: Pilkington Visioncare, Inc. · Inventors: Freeman, Michael Harold
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An artificial eye lens such as a contact lens or intra-ocular lens corrects astigmatism by two sets of substantially linear parallel zones arranged to diffract light predominantly into one order at one orientation, the spacing of the zones diminishing on either side of the linear axis. In addition circular diffraction zones may be provided to give both spherical and cylindrical power for astigmatism correction.
Read the whole patent
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 December 19, 1989 and granted April 27, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 19, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 19, 2011.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.