Fig. 2. Single-shot 3D reconstruction in PACTER.

a, Illustration of the calibration procedure of PACTER. Focused laser beams for calibration are shown in green. Calibration pixels are highlighted as orange dots. Calibration step size is 0.1 mm. The calibration pixels (80 × 80) become 6,400 virtual transducers. r₁, r₂, r₃, are the positions of three calibrated virtual transducers. b, Illustration of PACTER of human palmar vessels. The homogenized beam for widefield illumination is shown in green. $r_1^{\prime }$ and $r_2^{\prime }$ are the positions of two source points in the vessels. Blue and green spheres denote the PA waves generated by the source points. The calibrated virtual transducers capture the PA signals from $r_1^{\prime }$ and $r_2^{\prime }$ with different delays, indicated by the thick blue and green lines. c, PACTER signals, k₁(t), k₂(t), k₃(t), of the calibrated virtual transducers corresponding to r₁, r₂, r₃, respectively. d, PACTER signal from the widefield imaging consists of PA signals from $r_1^{\prime }$ and $r_2^{\prime }$, which are essentially k₁(t), k₂(t), k₃(t), delayed according to the distance between the calibrated virtual transducer and the source point.