Birefringent interference polarizer
CA 2056153 A1 · Owner: The Dow Chemical Company · Inventors: Wheatley, John A.; Schrenk, Walter J.; Chang, Victor S.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A birefringent interference polarizer which may be fabricated from readily available materials using established coextrusion techniques is provided. The polarizer has a level of light absorption near zero and can be fabricated to polarize and reflect light of specific wavelengths while transmitting light of other wavelengths. The polarizer includes multiple alternating oriented layers of at least first and second polymeric materials having respective nonzero stress optical coefficients which are sufficiently different to produce a refractive index mismatch between the first and second polymeric materials in a first plane which is different from the refractive index mismatch between the …
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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 November 25, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 25, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 25, 2013.
- 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.