Depth profiling of absorbing soft materials using photoacousticmethods

摘要

A Q-switched, frequency doubled, Nd:YAG laser coupled to annoptical parametric oscillator generated 4.75-ns laser pulses at 726 nmnto create subsurface acoustic waves in India ink solutions, India inknacrylamide gels, and in flat segments of elastin biomaterial stainednwith India ink. The acoustic waves traveled through the target and werendetected by a piezoelectric transducer. The waveforms were converted tonmeasurements of initial laser induced pressure and temperature asnfunctions of depth in the material. An algorithm based on Beer's Law wasndeveloped and applied to the acoustic signals to extract informationnabout the absorption coefficient as a function of depth in the samples