Bragg grating pressure sensor

US6422084B1 · kind B1 · utility

Assignee

• Weatherford/Lamb, Inc. · US

Inventors

• Mark R. Fernald · Enfield, US
• Timothy J. Bailey · Longmeadow, US
• Matthew B. Miller · Glastonbury, US
• James M. Sullivan · Manchester, US
• James Dunphy · South Glastonbury, US
• Michael A. Davis · Redwood City, US
• Christopher J. Wright · Bend, 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: Jul 23, 2002
• Expiry date: Dec 6, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L11/025
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A fiber grating pressure sensor includes an optical sensing element 20, 600 which includes an optical fiber 10 having a Bragg grating 12 impressed 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 which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20, 600 may be used by itself as a sensor or located within a housing 48, 60, 90, 270, 300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20, 600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50. At least a portion of the sensing element may be doped between a pair of gratings 150, 152, to form a compression-tuned laser or the grating 12 or gratings 150, 152 may be constructed as a tunable DFB laser. Also, the axial ends of element 20, …