Patent ID: 6680479
Filing Date: 2004-01-20
Classification: G01J,G01N

Abstract:
A method for detecting the presence of water on an inside surface of a conduit or pipes comprising:emitting an optical signal comprising at least a first wavelength and a second wavelength, both said wavelengths being absorbed by water with said first wavelength being absorbed to a greater extent than said second wavelength so that said second wavelength provides a reference; directing said optical signal onto said inside surface of said conduit or pipe from which the signal is reflected; alternately passing the reflected signal through a first optical filter which passes substantially only an optical signal of said first wavelength and through a second optical filter which passes substantially only an optical signal of said second wavelength; observing when the strength of a signal emergent from the first optical filter differs in a pre-determined way from the strength of the reference passed by the second optical filter to indicate the presence of water on said inside surface of said conduit or pipe; and moving a detection unit mounted on an extensible support along the interior of said conduit or pipe to perform said emitting step at different portions of said inside surface of said conduit or pipe.