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. 24, 1987
Filed:
Feb. 21, 1986
Friedrich-Karl Beckmann, Pinneberg, DE;
Wolfgang Hoppe, Norderstedt, DE;
Reinhard Knochel, Elmshorn, DE;
U.S. Philips Corporation, New York, NY (US);
Abstract
The invention relates to an optical time-domain reflectometer (OTDR) using heterodyne reception for determining the attenuation of an optical fiber guide by measuring the backscattered portion of light pulses launched into the fiber. The reflectometer comprises a light source whose light is split into a local-oscillator beam and a measuring beam. The measuring beam is pulsed by an acousto-optical modulator (AOM) and is then launched into the optical fiber to be tested. The measuring beam thus has a frequency which is offset from the optical frequency by an acoustic frequency. The local-oscillator beam and the back-scattered portion of the measuring beam are both directed to an optical receiver producing an electric output signal. A component of the output signal has a frequency corresponding to the acoustic frequency. The time-dependent amplitude of this component is a measure of the length-dependent attenuation of the optical fiber. In order to reduce the losses in the path between the light source and the optical receiver via the fiber to be tested, the acousto-optical modulator (AOM) also functions as an optical deflection element.