Patent ID: 6659640
Filing Date: 2003-12-09
Classification: G01K

Abstract:
A system for measuring the temperature to which a structure is subjected, comprising:an optical fiber configured to be positioned within an environment in which the structure is located; a coupler in optical communication with the optical fiber; first and second Bragg grating sensors formed within the optical fiber, each Bragg grating sensor being configured to have a particular sensor wavelength; a first material deposited over the first Bragg grating sensor, the first material having a first coefficient of thermal expansion, the first Bragg grating sensor having a coefficient of thermal expansion that is based predominately on the first coefficient of thermal expansion of the first material; a second material deposited over the second Bragg grating sensor, the second material having a second coefficient of thermal expansion that is significantly greater than the first coefficient of thermal expansion, the second Bragg grating sensor having a coefficient of thermal expansion that is based predominately on the second coefficient of thermal expansion of the second material; wherein the difference between the coefficient of thermal expansion of the first Bragg grating sensor and the coefficient of thermal expansion of the second Bragg grating sensor is greater than 10.0 micro-strain per degree Fahrenheit thereby providing a significant difference in temperature sensitivity between the first and second Bragg grating sensors; a light source in optical communication with the coupler for launching a broadband source of light into the optical fiber; a detector in optical communication with the coupler for detecting the light returning from the first and second Bragg grating sensors; a processor joined to said detector for measuring the strain response of each Bragg grating sensor due to the effects of temperature upon the Bragg grating sensors, determining the difference between the measured strain responses of each Bragg grating sensor, and determining the temperature to which the structure is subjected based on the measured difference between the measured strain responses; and an interface in data communication with said processor for inputting into said processor calibration data defining the coefficient of thermal expansion and identification of each Bragg grating sensor.