Photoacoustic determination of small optical absorption coefficients: extended theory.

Photoacoustic measurement of small absorption coefficients provides an important alternative to standard techniques. The theoretical basis for such measurements is extended to include the effects of thermally generated mechanical motion of the sample, by incorporating the thermoelastic equations for an isotropicm solid in a cylindrical configuration. Sample calculations show that this thermoacoustic effect may dominate the photoacoustic signal for certain modulation frequencies and beam configurations.