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:
Dec. 02, 1997
Filed:
Oct. 10, 1995
Nikon Corporation, Tokyo, JP;
Abstract
A minute step measuring method comprises forming a laser spot on an object by condensing light from a laser light source, condensing light beams from the object on an end face of a double-mode waveguide, branching light propagating in the double-mode waveguide into two channel waveguides, detecting light beams emerging from the two channel waveguides, and measuring a minute step existing on the object, using a signal of a difference and a signal of a sum between two signals according to the two light beams detected, wherein measurement is conducted of a signal W.sub.a of the sum when the laser spot is located on one of two flat portions existing before and after the step, and of a signal W.sub.b of the sum when the laser spot is located on the other flat portion, and wherein the step is measured by correcting a difference between reflectivities of the two flat portions existing before and after the step in measuring the minute step, using the signals W.sub.a and W.sub.b.