Photoacoustic determination of absolute optical absorption coefficient

We propose and demonstrate that the photoacoustic effect can be used for absolute determination of the optical absorption coefficient. The photoacoustic signal is measured as a function of chopping frequency and compared to the theory of the photoacoustic effect. The essential agreement of theory and experiment over a restricted frequency makes possible the determination of the optical absorption coefficient (to within 10% in a test case). Observation of a characteristic leveling off of the photoacoustic signal at low frequencies for several materials is also reported.