Solid state photoacoustics with laser pulse: mathematical model and experimental data filtering

Abstract

The first part of this paper presents theoretical analysis of the response of typical photoacoustic cell excited with a laser pulse absorbed by the sample located inside the cell and causing changes of temperature in the whole system. Pressure response curves provide information about optical and thermal properties of the sample. System of 1D heat conduction differential equations for each region of the cell has been solved. Changes of solid sample temperature, resulting from absorption of a laser beam warm up gas surrounding the sample. Changes of gas temperature are transferred into changes of its pressure, in result of thermodynamic processes in the gas filling photoacoustic cell and are detected with a microphone in a typical photoacoustic experiment. In the second part of the article a review of application of wavelet analysis for PT signal filtering is presented. The wavelet method is compared with Fourier transform and signal subtraction and seems to be very promising.