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:
Aug. 22, 2017
Filed:
Apr. 28, 2009
Applicant:
Robert Laird Stewart, Wigton, GB;
Inventor:
Robert Laird Stewart, Wigton, GB;
Assignee:
INNOVIA FILMS LIMITED, Wigton, Cumbria, GB;
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
G01B 9/02 (2006.01); G01B 11/06 (2006.01); G01N 21/23 (2006.01);
U.S. Cl.
CPC ...
G01B 11/0641 (2013.01); G01B 11/0675 (2013.01); G01N 21/23 (2013.01);
Abstract
A method of authenticating a polymer film comprises measuring the thickness of a layer therein by white light interferometry and/or measuring the birefringence of a layer therein. The method, and devices to carry out the method, may be used in security applications, for example to test for counterfeit bank notes.