An Optoacoustic Technique for Measuring the Optical Absorption Coefficient in Solids.

摘要

An investigation was made of an optoacoustic technique for determining the optical absorption coefficients in solids. A train of laser pulses was passed through the solid, and the amplitude of the acoustic wave generated by the absorbed radiation was measured by a piezoelectric transducer attached directly to the sample. It was shown theoretically and experimentally that the output voltage from the transducer was proportional to the absorbed energy. The generated voltage per unit of absorbed energy was established by measuring the output voltage at a laser wavelength of known absorption coefficient. This value was then used as a reference to determine the abosrption coefficient at other laser wavelengths. Measurements were made on various glasses and potential window materials. Absorption coefficients in the 10 to the -5th power/cm range were measurable with laser input powers of only a few hundred mW. The sensitivity of the technique was limited by the voltage generated by radiation scattered onto the transducer. (Author)