Patent ID: 8359903

Claim:
A photoacoustic detector for providing a measurement, comprising: a first light source and a second light source each configured to provide light of a same intensity while retaining a same spectral distribution; a first beam path allocated to the first light source; at least one second beam path allocated to the second light source, wherein a different absorption of light occurs in the first path and the second beam path in at least one selected wavelength range; a photoacoustic measuring cell; and a mechanism for alternately guiding light from the first beam path and from the second beam path into the photoacoustic measuring cell, wherein when alternately guiding light from the first beam path and from the second beam path into the photoacoustic measuring cell, the same intensity of the first light source and the second light source prevents generation of a photoacoustic signal due to light source intensity variation that distorts the measurement, the photoacoustic detector further comprising at least one absorption cell configured to absorb in selected wavelength ranges and positionable in the first beam path or the second beam path.