The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 04, 1997
Filed:
Nov. 15, 1995
Andre Tardy, Egly, FR;
Alcatel Cable, Clichy Cedex, FR;
Abstract
The present invention relates to a method of detecting and/or measuring changes in a physical magnitude by means of a distributed sensor, changes being detected and/or measured at a plurality of 'measurement' points along said sensor, said sensor comprising an optical fiber having an optical core for guiding the majority of light waves, said optical core including a plurality of diffraction gratings distributed along said optical fiber, each situated at one of said measurement points, said diffraction gratings all having substantially the same central reflection wavelength in the absence of strain, the method comprising the following steps: injecting a 'detection' light signal into an 'inlet' end of said optical fiber, the wavelength of the light signal being close to said central reflection wavelength; determining the power of one of the reflected signals, referred to as the 'detected reflected power', as a function of time; comparing said detected reflected power as a function of time with the power reflected as a function of time by the sensor in the absence of any change in said physical magnitude, referred to as the 'idle' reflected power; and detecting change in said physical magnitude whenever said detected reflected power differs from said idle reflected power.