Patent ID: 7675030

Claim:
A system configured with enhanced attenuation compensation for optically sampling characteristics of subsurface fluids within a wellhole, said system comprising: a source of light located outside a well; at least one optical fiber connected to said source of light for transmission of light to an operative location within the wellhole; at least one optical splitter connected to said optical fiber within said wellhole for splitting the beam of light into at least two channels of light, constituting at least one sampling channel and at least one reference channel, wherein the at least one sampling channel is as long as the at least one reference channel; a modulator connected downstream of said optical splitter to each of said at least one reference channel for modulating the light of each reference channel to which such modulator is connected; a modulator connected downstream of said optical splitter to each of said at least one sampling channel for modulating the light of each sampling channel to which such modulator is connected; an optical-to-electrical converter to power a galvanometer with light transmitted downhole though said optical fiber for switching light transmission in each channel; at least one wellhole fluids sampling cell operable to be positioned within the wellhole and connected to said at least one sampling channel within the wellhole; at least one optical coupler for joining light from said at least one sampling channel and said at least one reference channel and inputting said light into at least one optical fiber for return of information to the surface of said wellhole for analysis; and a signal detector and processor located outside the well and being connected to said optical fiber for analyzing signals received from said at least one fluids sampling cell and said at least one reference channel, said system having enhanced attenuation compensation based on a ratio of the signals received from the at least one wellhole fluids sampling cell and said at least one reference channel, a fraction ratio in splitting the beam of light into the at least two channels of light, and an optical attenuation between the at least one optical splitter and the at least one optical coupler.