Photoacoustic determination of optical parameters of biological tissue

Tissue optical properties are determined by an interpretation of pressure transients generated by irradiation with pulsed laser light. These pressure signals are detected using piezoelectric transducers. The signals are influenced by numerous processes during generation, propagation and detection. To study each process in particular, specific experiments were performed using biological tissue in vitro as well as different substances with various absorption and scattering properties. Especially acoustical diffraction effects cause a strong distortion of the shape and spatial oscillations in the amplitude of the transients. These phenomenons were investigated experimentally and verified theoretically.