Exemplary embodiments relate to an optical gas analyzer device that includes at least one measuring chamber in the form of a tubular measuring cuvette through which measuring gas flows. The measuring chamber is illuminated longitudinally by a radiation source that is arranged at an input end thereof and the light beam of which weakened by absorption losses is detected for gas concentration analysis by at least one detector arranged at an output end. The measuring process is calibrated using a reference spectrum. A special optical filter can be inserted into the measuring process in place of the measuring cuvette. The filter material of the filter generates a plurality of strong absorptions across the entire wavelength range of the measuring spectrum in order to cause attenuations that in the particular spectral position correspond to those of the gaseous measuring medium in greater concentration.