The thesis discusses the photoacoustic phenomenon, in which the absorption of amplitude modulated light in a substance causes, through intermediate conversion into heat, thermal expansion and contraction of the substance and thus the emission of sound waves.
The goal is to first study the theoretical background of the phenomenon, find out what physical properties the substance must exhibit and then practically test the phenomenon itself. At the same time, we explain why amongst carbon-based nanostructures, soot is susceptible to exhibiting this phenomenon. The discussion also addresses the possibility of improving the conversion efficiency by using a coating of a transparent elastomer, specifically polydimethylsiloxane (PDMS).
To test the emergence of the phenomenon, we designed a simple photoacoustic speaker with associated electronics for controlling a light-emitting diode with the use of an Arduino Uno development board. Subsequently, several experiments on samples of selected materials were carried out to capture and measure the strength of the sound produced by the phenomenon. Based on the obtained frequency spectra and previously performed optical characterization, a comparison of the photoacoustic conversion efficiency of the analyzed samples followed.
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