Abstract: The invention relates to a device comprising: a resonant tank (100) consisting of two primary tubes (105, 106) which are closed on the ends thereof and interconnected, close to each of the ends thereof, by two secondary tubes (109, 110), and provided with a gas-introducing means (118, 119); a first laser source (112) modulated to a first resonance frequency of the tank, which supplies an excitation energy in at least one of the primary tubes, with an emission wavelength corresponding to a local maximum absorption wavelength for a first gas, for generating a first stationary wave propagating along the secondary tubes; a second laser source (117) modulated to a second resonance frequency of the tank, which supplies an excitation energy in at least one of the secondary tubes, with an emission wavelength corresponding to a local maximum absorption wavelength for a second gas, for generating a second stationary wave propagating along the primary tubes; at least one acoustoelectric transducer (103, 104, 123, 124) a

Abstract: The photoacoustic device for measuring the quantity of at least one gas. The Helmholtz-type esonant container comprises at least two tubes closed at their ends and linked together, close to each of their respective ends, by capillary tubes of diameter lower than the diameter of the parallel tubes. Each of the two radiant laser energy sources is physically separated and adapted to supply an excitation energy to the gas in the container at a different emission wavelength. The modulation means modulates the excitation energy supplied by each laser energy source with a modulation frequency corresponding to the acoustic resonance frequency of the container. At least one acoustoelectric transducer disposed on one of the tubes detects the produced acoustic signals produced and supplies an electric signal representative of the gas concentration in the container.