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An experimental correction procedure is presented which allows one to measure separately and to eliminate signal contributions produced at the walls of photoacoustic cells by the directly incident light or by the light (diffusively) reflected from the solid sample. This stray-light correction procedure is tested for an opaque and a transparent photoacoustic cell. It helps to reduce the systematic error of photoacoustic measurements considerably when the solid to be analyzed and the reference material have different reflection properties and when in quantitative thermal depth profiling a larger interval for the modulation frequency of heating is needed.

Thermal diffusivities of metallic glass ribbons have been measured at different annealing stages by the photoacoustic method using a gas-coupled microphone. In a symmetrical excitation geometry of the photoacoustic experiment, heat waves were generated by a laser beam at both sides of the foils. Values of thermal diffusivities have been compared with those of the electrical conductivity measured on the same samples.