Abstract: A method for measuring an amount of a gas species able to absorb light in an absorption spectral band includes placing a gas between a measurement photodetector and a light source able to emit an incident light wave propagating through the gas to the photodetector. Electrical supply current passes through the light source to bring it to a temperature value. At multiple times: the light source illuminates the gas; the measurement photodetector measures a “measurement” intensity of a light wave transmitted by the gas in a measurement spectral band; and a reference photodetector measures a “reference” intensity of a reference light wave emitted by the light source in a reference spectral band. At each measurement time, a correction function representative of a variation in the incident light wave's intensity in the measurement band relative to in the reference spectral band is taken into account based on the measured reference intensity.

Abstract: A method for measuring an amount of a gaseous species present in a gas, the gaseous species absorbing light in an absorption spectral band, comprises placing the gas between a light source and a measuring photodetector. The light source is configured to emit a light wave that propagates through the gas to the measuring photodetector. The light source is activated so as to illuminate the gas, so that the light source emits a light pulse. The method also includes measuring, with the measuring photodetector, a measurement intensity of a light wave transmitted by the gas during the illumination, in a measurement spectral band. The measurement spectral band comprises the absorption spectral band. The light source is activated using a pulsed activation signal, each pulse having a specific form, notably to reduce aging of the source.