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:
Nov. 24, 1981
Filed:
May. 15, 1979
Karel Urbanek, Atherton, CA (US);
George J Kren, Los Altos, CA (US);
William R Wheeler, Saratoga, CA (US);
Tencor Instruments, Mountain View, CA (US);
Abstract
An instrument for computing resistivity based upon measurements of thickness and conductance. A conductance transducer is a solenoid in an annular ferrite cup connected to a tank circuit for an eddy current measurement of conductance. Within the center of the annular ferrite cup concentric acoustic wave sending and receiving channels are disposed for making an acoustic pressure wave measurement which is used for a thickness measurement using two gauge heads, spaced on opposite sides of an article to be measured. Each gauge head contains identical conductance and thickness transducers. The thickness measurement is divided by the conductance measurement to derive resistivity.