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:
Mar. 15, 1988
Filed:
Sep. 08, 1986
Hitachi, Ltd., Tokyo, JP;
Abstract
A method for examining a layer having defects and in particular the thickness of a machining damaged layer on a surface of a sample by means of a focused ultrasound beam and a device for realizing the method are disclosed, in which a focused ultrasound beam is generated and ultrasound reflected by the sample is detected. Curves (called V(z) curves) representing the relation of the distance between a transducer detecting the reflected ultrasound and the sample versus the detection output are traced while varying the distance and this measurement is repeated while varying the frequency of the focused ultrasound beam. The propagation velocity of surface acoustic wave in the sample is calculated on the basis of the period in each of the plurality of V(z) curves and a frequency dependence characteristic curve for the propagation velocity is obtained. The thickness of the machining damaged layer in the surface portion of the sample is evaluated from inflection points in the frequency dependence characteristic curve.