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. 24, 1997
Filed:
Aug. 28, 1995
Ronald V Alves, Palo Alto, CA (US);
Wayne V Sorin, Mountain View, CA (US);
Steven A Newton, Belmont, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
An apparatus and method for measuring the thickness of a film having top and bottom surfaces. The apparatus includes a first coupler for generating a first probe light signal and a second probe light signal from a low coherence light source. The first probe light signal is directed toward the top surface of the film and the light leaving the top surface of the film is collected. Similarly, the second probe light signal is directed toward the bottom surface of the film and the light leaving the bottom surface of the film is also collected. Top and bottom partially reflecting reference surfaces are provided for generating reflections. The top reference surface reflects part of the light leaving the top surface back toward the top surface, and the bottom reference surface reflects light leaving the bottom surface of the film back toward the bottom surface of the film. The collected light is combined to form a collected light signal which is input to a receiver that determines the time delay between light reflected from the top surface of the film and the top reference surface and between the bottom surface of the film and the bottom reference surface. In the preferred embodiment of the present invention, the receiver is constructed from an optical autocorrelator or an optical spectrum analyzer that includes circuitry for providing the Fourier transform of the frequency domain spectrum measured from the collected light signal.