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:
Feb. 13, 1979
Filed:
Feb. 17, 1977
Yau Y Hung, Rochester, MI (US);
Ralph M Grant, Rochester, MI (US);
Dr. Ralph M. Grant Engineering Consultants, Inc., Auburn Heights, MI (US);
Abstract
To obtain a photographic record of an object surface having superimposed interference fringes arrayed as a function of the deformation which results in the object from an applied stress, which may be mechanical, thermal, or the like, the object is first illuminated with coherent light. The illuminated surface is then photographed with a camera having an optical wedge disposed over half of its lens to record two slightly displaced overlapping images of the object on the camera film. The object is then stressed by changing the ambient temperature or pressure or other mechanical loading, and the undeveloped film is exposed to a second set of overlapping images. The developed photograph contains a set of equal amplitude fringes representing the interference pattern between the two fringe sets generated by the two exposures and arrayed as a function of the strain in the object as a result of the stress. To render the fringe set visible, an image of the object is projected on a screen through a Fourier, fringe-frequency sensitive filter which enhances the fringe contrast on the resulting image of the object.