The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 07, 2003
Filed:
Jan. 15, 2002
Applicant:
Inventor:
Keith L Lewis, Malvern, GB;
Assignee:
QinetiQ Limited, Farnborough, GB;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B 5/28 ;
U.S. Cl.
CPC ...
G02B 5/28 ;
Abstract
Optical filters ( ) designed in pairs, which are essentially colourless in their individual general appearance designed to take on a strong coloration when viewed together in transmission, said filters being particularly, useful for identification of counterfeit articles. The optical filters ( ) utilize resonantly-coupled Fabry-Perot etalons of, an asymmetric design. The filters ( ) are configured such that one of the Fabry-Perot cavities within the filter incorporates an additional multiple quarter wave thickness layer ( ), said additional layer having a contrasting refractive index to that of the cavity spacer.