20130205871 | METHOD AND DEVICE FOR DETECTING TRACE AMOUNTS OF MANY GASES - 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. | 08-15-2013 |