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. 03, 2009
Filed:
Mar. 02, 2007
Shigeru Serikawa, Nakai, JP;
Shigeru Serikawa, Nakai, JP;
Hitachi High-Technologies Corporation, Tokyo, JP;
Abstract
A method and an apparatus for measuring optical heterodyne interference in which a reference light and a measurement light differing in frequency is generated. The measurement light is S- or P-polarization light which is irradiated on a target through a polarization light beam splitter, and the reference light is P or S-polarization light which is reflected by a mirror. Interference of the measurement light from the target and the reference light reflected from the mirror is obtained by a light receiving element so as to measure a surface condition or detecting a surface detect on the target. A polarizing plate which is arranged before the light receiving element has an axis rotated so that a signal from the light receiving element becomes a minimum when the reference light is selectively shut off by a light shut off mechanism arranged before the polarization light beam splitter.