Patent ID: 6133573
Filing Date: 2000-10-17
Classification: G01N

Abstract:
A method for determining a gas volume concentration according to which:an electromagnetic radiation is emitted (state 1) through the gas volume,said radiation is filtered by temporally modulating the spectral transmission of a 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 extracted from it is a signal E depending in particular on the gas concentration, wherein:the component Eac(1) of the time-variable signal is isolated,the component Edc(1) of the signal, which is not a time-variable signal, is isolated,a radiation (state 0) stops being emitted, andthe component Eac(0) of the signal received by the detector is isolated,the component Edc(0) of this signal is isolated,the terms Eac(1)-Eac(0) and Edc(1)-Edc(0) are calculated,the ratio (Eac(1)-Eac(0))/(Edc(1)-Edc(0)) is formed which then solely depends on the gas concentration c and c is deduced from this.