Patent ID: 7703514

Claim:
A system for measuring at least one of the rate and direction of the flow of fluids in a conduit within a wellhole, said system comprising: a source of light located outside a well; a first optical fiber operable to extend into a wellhole connected to said source of light; an optical coupler in line with said first optical fiber; a second optical fiber connected to the said optical coupler; a signal detector and analyzer connected to said second optical fiber; and a sensor assembly connected downhole to said first optical fiber, including: an optical collimator attached to said first optical fiber, a Faraday crystal positioned optically downstream of said optical collimator, an optical reflecting device positioned optically downstream of said Faraday crystal operable for redirecting the light back through said first optical fiber and, ultimately, to the said signal detector and analyzer located at the well surface, wherein said sensor assembly is operable to detect light insertion losses as a function of perturbations in magnetic fields near said sensor; a decoder comprising at least one permanent magnet; and an impeller connected to said decoder and being operable to rotate as a result of fluids flowing within said wellhole conduit wherein the angular rotation of the impeller and decoder are equal in both direction of rotation and angular velocity.