Theoretical aspects of Photoacoustic Signal Generation with Solid Crystals

Abstract

Today, non-destructive analysis techniques play an important role in industrial applications and scientific, as well as technological research. Photoacoustic method is one of such non-destructive methods in which generation of acoustic waves takes place due to the absorption of the modulated incident radiation. Photoacoustic signal is a base for photoacoustic research. The generation of the photoacoustic signal is related to the nature of the cell used for investigation. Though a variety of explainations about signal generation in photoacoustic interaction are reported by many researchers, many aspects are yet to be studied in detail. While investigating a solid crystal in photoacoustics, factors as mode of operation, scheme of excitation, the shape of the cell, and pressure fluctuations in the cell are considered for analysing photoacoustic signal generation. Also, design and performance optimization of the photoacoustic cell play paramount role in determining efficiency of related signal generation. In this paper, theoretical aspects of photoacoustic signal generation for solid crystals are presented. While obtaining the expression for pressure fluctuations with solid crystal, cylindrical configuration of photoacoustic cell is preferred to get a better signal– to–noise ratio. Along with the analysis of other factors, pressure fluctuations generated by the enclosed gas in photoacoustic cell is mathematically determined.