Fig. 1.

Schematic of full-field optical interferometric imaging of photoacoustic waves at the specimen surface. (a) When an excitation pulse with a beam size of several millimeters is irradiated to the specimen, each absorber inside the specimen absorbs light energy and generates a pulse of acoustic wave. (b) The photoacoustic wave propagates toward the surface and induces displacement at the top surface of the cover layer, at $z=-d$. (c) By adjusting the time delay $t$ between the excitation and the probe pulses, the 2D displacement maps are captured in a time sequence. Color bars: phase in radians. (d) By taking time derivative with the acquired displacement maps, the pressure maps are calculated. These maps visualize the expansion or propagation of pressure waves with time. Color bar: scaled pressure. Scale bars in (c)-(d): 2 mm.