Patent ID: 7199869
Filing Date: 2007-04-03
Classification: E21B,G01D,G01K

Abstract:
1. A method for sensing attributes of reflected signals in an optical sensing system comprising an interrogator coupled to a Bragg grating sensor by an optical cable, the method comprising: producing a first optical signal with a light source, the first optical signal having a predefined wavelength range; coupling the first optical signal to an optical cable; receiving a first reflected signal of the first optical signal, the first reflected signal from a Bragg grating sensor within the optical cable; resolving an attribute of the first reflected signal indicative of an environmental condition at the Bragg grating sensor; producing a second optical signal with the light source, the second optical signal at a predefined wavelength; coupling the second optical signal to the optical cable; receiving a second reflected signal of the second optical signal, the second reflected signal caused by Brillouin backscattering within the optical cable; and resolving a shift in attribute between the second optical signal and second reflected signal that is indicative of an environmental condition along the optical cable.