Research on photoacoustic effect of picosecond laser pulse with tissue based on finite element method

Photoacoustic imaging technology is an emerging functional imaging method in the field of biomedical applications. It combines the light absorption characteristics of tissues with the advantages of ultrasonic detection, and has the advantages of strong contrast, high sensitivity, and deep imaging depth. Therefore, this article uses the finite element software COMSOL Multiphysics to study the relationship between ultrashort laser pulses and the generated photoacoustic signals. In COMSOL, a laser with a pulse width of 5 ps is used as the excitation light source. Use mathematics module, heat transmission module, etc. to simulate the process of photothermal conversion-thermal expansion-generation of ultrasound in the photoacoustic imaging of the tissue-absorber system. In this way, the photoacoustic signal and its image are obtained. This study provides a theoretical basis for the application of picosecond laser pulses in photoacoustic imaging.