Measurement and analysis of photoacoustic pressure induced by weak microsecond pulsed light

The photoacoustic effect (PAE) of weak microsecond pulsed light (WMPL) has immense potential for application to biomedical engineering. However, practical measurements and theoretical analysis of the photoacoustic pressure of WMPL are lacking. Hence, we constructed a WMPL photoacoustic pressure measurement system using an electret piezoelectric sensor and multi-wavelength parameter-adjustable pulsed light generator. Based on the system, the photoacoustic pressure interacting with the air medium induced by the WMPL with different optical parameters was measured. The measured pressure data were analyzed using the fixed variable method, and the pressure response characteristic was obtained. It was found that the measured results conform to the law of energy conversion but have a specific trend for some wavelengths. The analysis and discussion were conducted based on the classical wave equation of the PAE, and the extended wave equation was presented. It is shown that the proposed approach provides a reliable basis for the measurement and analysis of WMPL photoacoustic pressure.