(a) (i) System schematic and (ii) scanning mechanism of the large-FOV OR-PAM using a 2D galvanometer scanner and a cylindrical focused US transducer. black arrows: optical scan line, green bar: acoustic focal zone, dotted arrow: rotational scanning trace; FOV, field of view; OR-PAM, optical-resolution photoacoustic microscopy; L, lens; UST, ultrasound transducer. (b) Schematic of the galvanometer scanner OR-PAM using a non-conducting liquid. GM, galvanometer; CL, condenser lens; PEM, polyethylene membrane; TG, target; and OR-PAM, optical-resolution photoacoustic microscopy. Reprinted with permission from Ref. [88,89].