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.:

US 7539422 B1

PDF
Full Text
Expired
Date of Patent:
May. 26, 2009

Filed:

Apr. 20, 2005
Applicant:

Tatsuya Tomaru, Hatoyama, JP;

Inventor:

Tatsuya Tomaru, Hatoyama, JP;

Assignee:

Hitachi, Ltd., Tokyo, JP;

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04B 10/00 (2006.01);
U.S. Cl.
CPC ...
Abstract

In an optical detection method that requires a reference light such as homodyne detection, a signal light and the reference light must be equal to each other in the wavelength, and the phase relation between them must be maintained constant. In order to satisfy this requirement, the signal light and the reference light are extracted from the same light source and made equal to each other in the wavelength. The signal light and the reference light are transmitted so as to be temporally superimposed on each other with orthogonal polarizations to the same optical path, thereby making the external environments equal to each other to maintain the constant phase relation.


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