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Expired Canadian patentCanada

Polycrystalline zinc sulfide and zinc selenide articles having improved optical quality

CA 1181557 A · Owner: Raytheon Company · Inventors: Willingham, Charles B.; Pappis, James

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Abstract From the Canadian patent

Abstract, Articles of polycrystalline zinc sulfide and zinc selenide achieve substantially improved optical quality by a treatment of heat and isostatic pressure by means of an inert working fluid. The treated specimens are transparent and have substantial transmission in the infrared and visible range of the spectrum. Additional improvement in the transmission characteristics is achieved by wrapping the specimens in a foil of an inert material prior to treatment.

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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

  • Granted January 29, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended January 29, 2002.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledNovember 6, 1981
GrantedJanuary 29, 1985
Term endedJanuary 29, 2002
Patent numberCA 1181557 A
Classification (IPC)G02B1/00 +2 more

Timeline

Timeline From CIPO dates

1982198519881991199419972000Application filedNov 6, 1981Patent grantedJan 29, 1985Term endedJan 29, 2002

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.