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. 25, 1992
Filed:
Nov. 08, 1990
John Tyson, II, Wayne, PA (US);
Laser Technology, Inc., Norristown, PA (US);
Abstract
The purpose of the present invention is to improve the quality of a video signal generated by the method of nondestructive testing known as electronic shearography. In electronic shearography, two laterally-displaced images of a test object are made to interfere, and the interference pattern is stored. Another such interference pattern is obtained while the object is stressed. The two patterns are compared by computer, such as by subtracting one pattern from the other, and the resulting composite pattern is displayed on a video monitor or equivalent. According to the present invention, the subtracted signal is connected to a rectifier circuit which causes both positive-going and negative-going variations in the video signal to become positive-going variations. Thus, any changes in the intensity of the signal, due to phase changes resulting from deformation of the object, are displayed as increases in brightness of a pixel on the final display. If a point on the object has not moved due to the applied stress, the pixels representing that point remain dark. The present invention therefore produces an image having a greater resolution than is possible using the methods of the prior art.