Schmidt, StefanThévenaz, Luc2015-01-062015-01-062015-01-061997https://infoscience.epfl.ch/handle/20.500.14299/109914A method and apparatus serve to determine spectroscopically a concentration of ethanol in a test sample of an alcoholic aqueous beverage. The determination is based upon providing calibration data which establish a relation between (A) a plurality of transmission values of an electromagnetic radiation in the near infrared region, measured at a unique wavelength at which water is relatively opaque to the radiation while ethanol is relatively transparent thereto, of a plurality of calibration samples of the beverage containing ethanol in differing known concentrations, and (B) the known concentrations of ethanol in the calibration samples. Then, at least one light transmission value of the test sample at the unique wavelength, at which said calibration data were established, is measured. The measured transmission value of the test sample is transformed, by way of the relation established by the calibration data, into an indication of the concentration of ethanol in the test sample.patentEP0760479US5679955JPH09113441EP0760479ZA960431921702595