Fig. 5.

(A) Two-dimensional image of chicken breast tissue in which two gizzard objects were buried, reprinted with permission from [153]. (B) Interferometric detection of object surface displacement after photoacoustic excitation. © Institute of Physics and Engineering in Medicine. Reproduced by permission of IOP Publishing [155]. All rights reserved. (C) Schematic setup for specklegram-based non-contact photoacoustic detection. BS, beamsplitter; CMOS, CMOS camera; L, lens; PD, photodiode; SF, spectral filter. Speckle pattern generated by the probe beam observed for various moments (i)–(ix) in (a). Among them, (i) is the initial speckle pattern, (ii) and (iii) are recorded when the shutter is off, and no excitation beam is illuminated on the sample, and (iv)–(ix) are a sequence of patterns associated with the excitation of PA effect. (a) Measured speckle correlation changes as a function of excitation pulse energy (right axis) and the ultrasound piezoelectric transducer-based PA amplitude as a function of excitation pulse energy (left axis). (b) Linearity between the two detection methods, reprinted with permission from [156].