Method and gas sensor for performing quartz-enhanced photoacoustic spectroscopy

A method for performing quartz-enhanced photoacoustic spectroscopy of a gas, comprising:

• providing a light source configured to introduce a laser beam having at least one wavelength into the gas such that said at least one molecule within the gas is stimulated generating an acoustic signal,
• accumulating the acoustic signal in a resonant acoustic detector,
• generating a resonant absorption signal (SA) relative to the gas concentration by at least one tuning fork serving as resonant acoustic detector,
• generating additionally a resonant intensity signal (SI) proportional to the intensity of the laser beam travelling through the gas,
• providing an output signal (SGC) from said absorption signal (SA) and said intensity signal (SI) being independent of the intensity of the light relative to the presence or concentration of the gas,
• generating said resonant absorption signal (SA) by passing the light between the prongs of the said at least one tuning fork, and
• generating said resonant intensity signal (SI) by said at least one further tuning fork arranged in series to said at least one tuning fork, now serving as first tuning fork, such said the light incidents mainly on the prongs of said at least one second tuning fork.

A photoacoustic gas detector comprising:

• a light source for providing a laser beam,
• a detection region provided for receiving at least one sample gas,
• at least one first tuning fork serving as resonant acoustic detector and providing a resonant absorption signal (SA),
• processing means for providing a signal (SGC) relative to the presence or concentration of a given gas in said detection region, and
• at least one second tuning fork arranged in series to said at least first tuning fork, said at least one second tuning fork serving as resonant acoustic detector for providing a resonant signal relative to the intensity of the laser beam travelling through said sample gas.