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. 09, 1999
Filed:
May. 28, 1997
Applicant:
Inventor:
Shoei Ebisawa, Konosu, JP;
Assignee:
Dainippon Ink And Chemicals, Inc., Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
702167 ; 702155 ;
Abstract
A method for measuring dishing in discs, including the steps of irradiating a laser beam along a scanning line which spirals from an inner side to an outer side of a surface of a magneto-optical disc or a digital video disc; determining a tilt angle at each of a plurality of measurement points on the scanning line based on displacement of a reflected laser beam from a normal reflected position; and using a measurement point on a first circuit on the inner side of the scanning line as a reference to determine dishing amounts at corresponding measurement points on circuits after the first circuit based on the tilt angles.