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:
Jan. 01, 2002
Filed:
Apr. 11, 2000
Haruyoshi Uchiyama, Tokyo, JP;
Toshio Kurashima, Tokyo, JP;
Other;
Abstract
The present invention relates to an optical-fiber characteristics measuring apparatus that does not require frequency conversion of pulse light which enters an optical fiber to be measured, and does not restrict the cycle period of the pulse light, thereby ensuring fast measuring of the characteristics of the optical fiber. This apparatus comprises an optical directional coupler, an optical pulse generator, a balanced-light reception circuit, a signal generation section and a mixer. The optical directional coupler branches coherent light into first and second coherent lights. The optical pulse generator converts the first coherent light into pulse light which in turn enters an optical fiber to be measured. Returned light whose frequency is shifted from that of the first coherent light by a predetermined frequency through reflection and scattering in the optical fiber to be measured enters the balanced-light reception circuit. The balanced-light reception circuit carries out balanced-light reception of the second coherent light and the returned light and converts the resultant light into an electric signal. The signal generation section generates an RF signal whose frequency is equal to the predetermined frequency. The mixer mixes the electric signal and the RF signal to thereby detect the shifted frequency.