Morphology-dependent resonance enhanced nonlinear photoacoustic effect in nanoparticle suspension: a temporal-spatial model
Photoacoustic (PA) technique has become the focus of intensive research in noninvasive biomedical imaging during the last two decades [1,2]. In most optical imaging applications, the strong optical diffusion coefficient in biological tissues imposes severe challenges on deep penetration imaging. PA technique breaks the optical limit by effectively harnessing both high ultrasonic penetration and excellent optical specificity; it successfully demonstrates optical contrast imaging at several centimeters of biological imaging depth [3–5]. The basics of the PA technique is the conversion of absorbed photons into ultrasound via the transient thermoelastic expansion, where the contrast mainly results from the variation in the absorber’s optical absorption properties.