Temperature sensor using an optical fiber

Abstract

A temperature sensor that has an elongated sensing element having a length of at least 10 m, measured at a temperature of 20° C. The elongated sensing element includes an elongated jacket and an optical fiber mounted in the jacket and having an EFL of at least 0.35%, wherein the elongated sensing element has an average temperature error of less than 2° C.

1 . A temperature sensor, comprising:
 an elongated sensing element having a length of at least 10 m, measured at a temperature of 20° C., the elongated sensing element including:   an elongated jacket;   an optical fiber mounted in the jacket and having an EFL of at least 0.35%; and   the elongated sensing element having an average temperature error of less than 2° C.   
   
   
       2 . A temperature sensor as defined in  claim 1 , wherein the elongated sensing element has an average temperature error of less than 1° C. 
   
   
       3 . A temperature sensor as defined in  claim 2 , wherein the elongated sensing element has an average temperature error of less than 0.2° C. 
   
   
       4 . A temperature sensor as defined in  claim 1 , wherein the optical fiber has an EFL of at least 0.50%. 
   
   
       5 . A temperature sensor as defined in  claim 4 , wherein the optical fiber has an EFL of at least 0.70%. 
   
   
       6 . A temperature sensor as defined in  claim 1 , wherein the elongated sensing element has a length of not less than 100 m. 
   
   
       7 . A temperature sensor as defined in  claim 6 , wherein the elongated sensing element has a length of not less than 500 m. 
   
   
       8 . A temperature sensor as defined in  claim 7 , wherein the elongated sensing element has a length of not less than about 1 km. 
   
   
       9 . A temperature sensor as defined in  claim 1 , wherein the jacket is characterized by a CTEjacket, the optical fiber is characterized by a CTEfiber, and a ratio CTEjacket/CTEfiber has a value of at least about 1.0001. 
   
   
       10 . A temperature sensor as defined in  claim 9 , wherein the ratio CTEjacket/CTEfiber has a value of at least about 10. 
   
   
       11 . A temperature sensor as defined in  claim 10 , wherein the ratio CTEjacket/CTEfiber has a value of at least about 20. 
   
   
       12 . A temperature measurement system, comprising:
 an elongated sensing element having a length of at least 10 m, measured at a temperature of 20° C., the elongated sensing element including:   an elongated jacket;   an optical fiber mounted in the jacket and having an EFL of at least 0.35%;   the elongated sensing element having an average temperature error of less than 2° C.;   the optical fiber defining an optical path for conveying an optical signal, the optical path manifesting an interaction with the optical signal, the interaction producing a measurable response, the response conveying information about temperature to which the optical fiber is exposed; and   a measurement component coupled to the optical fiber to sense the response and for deriving from the response information on the temperature to which the optical fiber is exposed.   
   
   
       13 . A temperature measurement system as defined in  claim 12 , wherein the elongated sensing element has an average temperature error of less than 1° C. 
   
   
       14 . A temperature measurement system as defined in  claim 13 , wherein the elongated sensing element has an average temperature error of less than 0.2° C. 
   
   
       15 . A temperature measurement system as defined in  claim 12 , wherein the optical fiber has an EFL of at least 0.50%. 
   
   
       16 . A temperature measurement system as defined in  claim 15 , wherein the optical fiber has an EFL of at least 0.70%. 
   
   
       17 . A temperature measurement system as defined in  claim 12 , wherein the elongated sensing element has a length of not less than 100 m. 
   
   
       18 . A temperature measurement system as defined in  claim 17 , wherein the elongated sensing element has a length of not less than 500 m. 
   
   
       19 . A temperature measurement system as defined in  claim 18 , wherein the elongated sensing element has a length of not less than about 1 km. 
   
   
       20 . A temperature measurement system as defined in  claim 12 , wherein the jacket is characterized by a CTEjacket, the optical fiber is characterized by a CTEfiber, a ratio CTEjacket/CTEfiber has a value of at least about 1.0001. 
   
   
       21 . A temperature measurement system as defined in  claim 20 , wherein the ratio CTEjacket/CTEfiber has a value of at least about 10. 
   
   
       22 . A temperature measurement system as defined in  claim 21 , wherein the ratio CTEjacket/CTEfiber has a value of at least about 20. 
   
   
       23 . A temperature measurement system as defined in  claim 12 , wherein the measurement component is operative for deriving from the response information on the temperature to which the optical fiber is exposed at a plurality of spaced apart locations along the length of the sensing element. 
   
   
       24 . A temperature measurement system as defined in  claim 23 , wherein the optical fiber includes a plurality of spaced apart gratings having a temperature dependant response to optical interrogation. 
   
   
       25 . A temperature measurement system as defined in  claim 23 , wherein the interaction is a continuous interaction that occurs along the optical path, wherein the interaction produced back-scattering, the measurement component sensing the back-scattering. 
   
   
       26 . A temperature sensor, comprising:
 an elongated sensing element having a length of at least 10 m, measured at a temperature of 20° C., the elongated sensing element including:   an elongated jacket;   an optical fiber mounted in the jacket and having an EFL of at least 0.35%; and   the elongated sensing element having an S value of at least about 1 mm2 per percent of EFL.   
   
   
       27 . A temperature sensor as defined in  claim 26 , wherein the elongated sensing element has an S value of at least about 6.25 mm2 per percent of EFL. 
   
   
       28 . A temperature sensor as defined in  claim 27 , wherein the elongated sensing element has an S value of at least about 10 mm2 per percent of EFL. 
   
   
       29 . A temperature sensor as defined in  claim 26 , wherein the optical fiber has an EFL of at least 0.50%. 
   
   
       30 . A temperature sensor as defined in  claim 29 , wherein the optical fiber has an EFL of at least 0.70%. 
   
   
       31 . A temperature sensor as defined in  claim 26 , wherein the elongated sensing element has a length of not less than 100 m. 
   
   
       32 . A temperature sensor as defined in  claim 31 , wherein the elongated sensing element has a length of not less than 500 m. 
   
   
       33 . A temperature sensor as defined in  claim 32 , wherein the elongated sensing element has a length of not less than about 1 km. 
   
   
       34 . A temperature sensor as defined in  claim 26 , wherein the jacket is characterized by a CTEjacket, the optical fiber is characterized by a CTEfiber, and a ratio CTEjacket/CTEfiber has a value of at least about 1.0001. 
   
   
       35 . A temperature sensor as defined in  claim 34 , wherein the ratio CTEjacket/CTEfiber has a value of at least about 10. 
   
   
       36 . A temperature sensor as defined in  claim 35 , wherein the ratio CTEjacket/CTEfiber has a value of at least about 20.