Heterodyne optical time domain reflectometer

US5082368A · kind A · utility

Assignee

• U.S. Philips Corporation · US

Inventors

• Manfred Fuchs · Nuremberg, DE
• Wolfgang Hoppe · Linz, DE
• Friedrich-Karl Beckmann · Pinneberg, DE
• Ernst Brinkmeyer · Kürten, DE
• Wolfgang Brennecke · Hamburg, DE

Key dates

• Filing date: Oct 3, 1990
• Grant date: Jan 21, 1992
• Expiry date: Oct 3, 2010

Classification

• Technology area (CPC G): Physics
• CPC primary: G01M11/3109
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Heterodyne optical time domain reflectometer (OTDR) for determining the attenuation behavior of a monomode waveguide (test waveguide) by measurement of the backscattered parts of light pulses transmitted in said waveguide. An acousto-optic modulator (AOM) which deflects the transmission beam from a laser into the waveguide to be tested at a light frequency which is modulated with the acoustic frequency when the AOM is acoustically energized in a pulse mode. The light pulses backscattered from the test waveguide are superimposed on a local oscillator beam (LO) constituted by the laser beam which traverses the AOM when the AOM is not energized. The optical system losses are reduced in that the superposition is realized in a passive coupler, particularly a fibre coupler (10, 26).