Method for estimating the intensity of a wave emitted by an emitting source

A method for analyzing a gas sample, by comparison between a light wave incident on the sample and a light wave transmitted by the sample, the method comprising:

• i) illuminating the sample, with a light source, the light source emitting an incident light wave that propagates to the sample;
• ii) detecting, with a measurement photodetector, a transmitted light wave transmitted by the sample, the transmitted light wave resulting from an attenuation of the incident light wave by the sample;
• iii) detecting a reference light wave with a reference photodetector, the reference light wave being emitted by the light source, the reference light wave being representative of a light wave reaching the reference photodetector without interaction with the sample;
• iv) reiterating i) to iii) at various measurement times;
• v) from each reference light wave detected in each step iii), at each measurement time, estimating an intensity of the reference light wave at the measurement times, by implementing:
• b) estimating an intensity of the reference light wave at a measurement time based on an initial intensity or an estimation of the intensity of the reference light wave at a prior measurement time;
• c) measuring an intensity of the reference light wave detected at the measurement time;
• d) updating the estimation of the intensity of the reference light wave at the measurement time, depending on the intensity measured in c) and the intensity estimated in b);
• and
• e) reiterating b) to d), on the basis of the estimation of the intensity of the reference light wave obtained in d), while incrementing the measurement time;
• vi) taking into account the intensity of the reference light wave estimated, at each measurement time, including the estimated intensity resulting from v), and an intensity of the transmitted light wave detected in ii) and performing a comparison, at each measurement time, based on the reference light wave and on the transmitted light wave transmitted by the sample;
• and
• vii) analyzing the gas sample depending on the comparison performed in vi).