Objective lens having a doublet lens with high numerical aperture
CA 2218675 A1 · Owner: Watanabe, Toshio · Inventors: Watanabe, Toshio; Ichimura, Isao; Ohsato, Kiyoshi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An objective lens having a doublet structure and a number of apertures of 0.7 or more and an optical pickup apparatus having the objective lens to be adaptable to a optical recording medium having a high information recording density the objective lens being structured such that at least one side is formed into a aspheric surface and the lens elements are made of low-diffusion glass having an Abbe's number of 40 or greater.
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 October 21, 1997. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended October 21, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 21, 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.
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.