Resolving Acoustic Temporal Aliasing in High‐Throughput Photoacoustic Microscopy Through Spatial Division Multiplexing

ABSTRACT Laser pulse repetition rate (PRR) is a critical factor determining the spatial‐bandwidth‐product of high‐throughput photoacoustic microscopy (PAM). However, there exists a fundamental conflict between PRR and effective imaging depth for high‐throughput PAM, which causes acoustic temporal aliasing due to limited acoustic velocities in biological tissues. To overcome this issue, we propose a spatial division multiplexing scheme that utilizes multiple independent laser scan engines and an ultrasound transducer array to achieve parallel optical scanning and acoustic detection. Based on the proposed scheme, we reach an equivalent 6‐MHz laser PRR using a 1.5‐MHz pulsed laser and improve the imaging spatial‐bandwidth‐product by 4‐fold without scarifying the effective imaging depth. To demonstrate the superior advantage of this scheme, we develop a PAM system and perform high‐throughput vascular imaging of the mouse cerebral cortex with a field‐of‐view over 42 mm 2 , a spatial resolution of 4.3 µm, an effective imaging depth of 1 mm, and a maximum frame rate of 5 Hz.