An Analytical Expression Of The Photoacoustic Signal For A Pulsed Laser With A Sinusoidal Radial Profile

OpenAlex İngilizce

Photoacoustic signal depends on several laser factors, particularly the pulse duration, energy, wavelength, beam-width and repetition rate of the pulsed laser. Although these dependencies are well tested through experiments, they can also be investigated via theoretical approaches for the research into photoacoustic signal generation in parallel to advances in laser technologies. In this study, the photoacustic signal is presented analytically by solving the photoacoustic wave equation for an optical absorber heated up by a pulsed laser. The spatial and temporal parts of the pulsed laser are modeled by a sampling (sinc) function and a Gaussian function, respectively. The radial profile obtained experimentally by using a spatial light modulator can be modeled accurately with a sampling function. Pulsed lasers can lead to nonlinear effects. This nonlinear mechanism has various advantageous for the photoacoustic imaging. These short pulsed lasers have a close-to-sinusoidal variation in the central pulse region so that the spatial part of the laser is modeled by a sampling function in this work. For the photoacoustic wave, a detailed expression is obtained analytically in terms of the pulse duration and beam-width. The photoacoustic signal is observed in terms of time for various detector positions. Moreover, a detailed analysis is conducted to obtain a correlation between the photoacoustic signal and the laser factors. Therefore, the resulting quantification of the physical laser factors can offer a useful theoretical guide for the applications of photoacoustics. The sampling modeling presented by this study can also be helpful for the understanding of the nonlinear mechanism in photoacoustics.