Schlumberger Industries, Sa

Juan Pedro Silveira

Alain G Bazin

Francedillaois Grasdepot

A gas volume concentration is determined. An electromagnetic radiation is emitted (state 1) through the gas volume. The radiation is filtered by temporally modulating the spectral transmission of said filter so as to obtain a temporal modulation of the energy of the radiation transmitted by the gas volume and this filter. This temporally modulated energy is detected and a signal E is extracted from it, the signal particularly depending on the concentration of the gas. The component Eac(1) of the time-variable signal and the component Edc(1) of the signal, which is not a time-variable signal are isolated. A radiation stops is emitted (state 0), and the component Eac(0) and the component Edc(0) of the signal received by the detector are isolated. The terms Eac(1)-Eac(0) and Edc(1)-Edc(0) are calculated, and the ratio (Eac(1)-Eac(0))/(Edc(1)-Edc(0)) is formed which then solely depends on the gas concentration c. From this, c is deduced.

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Madrid, Spain

Juan Pedro Silveira