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:
Jun. 26, 2007
Filed:
Mar. 30, 2005
Mary Ann Johnson, Rockport, MA (US);
David W. Johnston, Kensington, NH (US);
Mary Ann Johnson, Rockport, MA (US);
David W. Johnston, Kensington, NH (US);
Osram Sylvania Inc., Danvers, MA (US);
Abstract
A method of making a standard tool for calibrating polarimeters that analyze stress in photoelastic material, includes the steps of partially annealing a starting piece of tempered glass so that the starting piece has a retardance below 250 nm/cm, removing a peripheral portion of the starting piece (preferably, at least about 20% of its radial dimension) to leave a working piece, cutting a rectangular parallelepiped from the working piece, polishing two opposing faces of the rectangular parallelepiped where the two opposing faces are spaced apart by a measurement distance through which light passes during stress analysis in a polarimeter, and determining a birefringence of the rectangular parallelepiped across the measurement distance using a calibrated polarimeter. The standard tool is the rectangular parallelepiped having the determined birefringence for the measurement distance. The method can be used to make a set of the standard tools with different measurement distances.