Fig. 1: High-speed PAM based on water-immersible scanners.

a Schematic of the galvanometer-scanner-based OR-PAM with the galvanometer in a non-conducting liquid. GM, galvanometer; OUC, opto-ultrasound combiner; UT, ultrasound transducer; CL, condenser lens; OL, objective lens; PH, pinhole; PEM, polyethylene membrane; TG, target. (adapted with permission from ref. ²³). b Schematic of a MEMS-scanner-based OR-PAM system. CL, condenser lens; AC, aluminum coating; AL, acoustic lens; UT, ultrasonic transducer (adapted with permission from ref. ²⁶). c Schematic of a polygon-scanner based OR-PAM system (left). AC, aluminum coating; HM, hexagon mirror; UST, ultrasonic transducer. The 3D drawing and photograph of the hexagon scanning mirror driven by a high-speed DC-motor are also shown (adapted with permission from ref. ³⁰).