Temperature insensitive fiber-optic torque and strain sensor

Patent 6513390 Issued on February 4, 2003. Estimated Expiration Date:

November 1, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

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Inventors

Assignee

McMaster University

Application

No. 703230 filed on 11/01/2000

US Classes:

73/800Optical

Examiners

Primary: Oen, William
Assistant: Dickens, Charlene

Attorney, Agent or Firm

International Class

G01L 001/24

Abstract

The present invention provides a simple design for a temperature-insensitive extrinsic polarimetric strain sensor. The sensing element is a thin sheet of photoelastic material that is bonded to the test object. It is illuminated with linearly polarized light with the polarization direction at 45 degrees relative to the strain-induced fast and slow axes in the photoelastic material. The sensor measures the difference between the strains along these two orthogonal directions. The reduced sensitivity of the sensor to temperature results from the fact that the illumination is perpendicular to the surface of the test object. All polarization components that are parallel to the surface will experience identical refractive index changes due to thermal effects. Consequently, a measurement of the difference in strains along two directions in the surface plane is insensitive to temperature.

Other References

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