Fig. 3: Phase mapping of ultrasound wavefront based on the projected light intensity patterns.

A Schematic of setup: light projection unit for illuminating defined intensity pattern (i), single power source unit, and transducer array for emitting ultrasound wavefront (ii). (iii) The photograph of the integrated transducer operated at the frequency of 0.7 MHz (scale bar 30 mm). The hydrophone scan is performed 1.5 mm above the transducer array. B The projected light intensity patterns represented by A (i) which are spatially structured to describe the formation of numerical digits (i) ''0'', (ii) ''1'', (iii) ''2'', (iv) ''3'', (v) ''4''. The maximum projected intensity is 65.7 mW/cm². C, D (i)–(v) The spatial distribution of the amplitude and the achieved phase shift in the pressure wave recorded by the hydrophone. The scan area is 31 × 31 mm. Scale bar indicates 7.5 mm.