Active coherence reduction for interferometer interrogation

US7433045B2 · kind B2 · utility

Assignee

• OPTOPLAN AS · NO

Inventors

• Erlend Ronnekleiv · Trondheim, NO
• Ole Henrik Waagaard · Trondheim, NO
• Kjell Blotekjaer · Trondheim, NO
• Dag Thingbo · Vikhammer, NO
• Sigurd Lovseth · Trondheim, NO
• Sverre Kundsen · Trondheim, NO

Key dates

• Filing date: Oct 8, 2004
• Grant date: Oct 7, 2008
• Expiry date: Feb 28, 2026

Classification

• Technology area (CPC G): Physics
• CPC primary: G01D5/35312
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Methods and apparatus reduce coherence of an optical signal that is used to interrogate optical interferometric sensors. The optical field phasor of the interrogation source is modulated in a controlled manner to produce a broadened optical source power spectrum at the output of the source unit. The output from the source unit is launched into an optical sensor network, comprising a multiple of optical pathways from its input to the detection unit, where pairs of optical pathways form sensor interferometers. A compensating interferometer with delay difference similar to the sensor delay difference may be arranged in a serially coupled manner with the optical sensor network, either before or after the network. The coherence modulation may be performed through direct modulation of the source or through external modulation of the light with piezoelectric ring modulator, a Lithium niobate phase or intensity modulator, or an acoustooptic modulator.