Strain-isolated Bragg grating temperature sensor

US6865194B1 · kind B1 · utility

Assignee

• CiDRA Corporation · US

Inventors

• Christopher J. Wright · Bend, US
• Mark R. Fernald · Enfield, US
• Timothy J. Bailey · Longmeadow, US
• James M. Sullivan · Manchester, US
• James Dunphy · South Glastonbury, US
• Michael A. Davis · Redwood City, US
• Alan D. Kersey · Burke, US
• Martin A. Putnam · Cheshire, US
• Robert N. Brucato · Waterbury, US
• Paul E. Sanders · Madison, US

Key dates

• Filing date: Dec 6, 1999
• Grant date: Mar 8, 2005
• Expiry date: Dec 6, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G01K11/32
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A strain-isolated bragg grating temperature sensor includes an optical sensing element 20,600 which includes an optical fiber 10 having at least one Bragg grating 12 disposed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and having the grating 12 disposed therein, which senses temperature changes but is substantially not sensitive to strains on the element caused by the fiber or other effects. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength λ1. The shape of the sensing element 20,600 may be other geometries and/or more than one concentric tube may be used or more than one grating or pair of gratings may be used or more than one fiber or optical core may be used. At least a portion of the element 20,600 may be doped between a pair of gratings 150,152, disposed therein to form a temperature tunable laser or the grating 12 or gratings 150,152 may be constructed as a temperature tunable DFB laser disposed in the element. Also, the element may have an inner or outer tapered regions 22,27, respectively, to provide strai…