Multifocal photoacoustic microscopy using a single-element ultrasonic transducer through an ergodic relay

摘要

Optical-resolution photoacoustic microscopy(OR-PAM)has demonstrated high-spatial-resolution imaging of optical absorption in biological tissue.To date,most OR-PAM systems rely on mechanical scanning with confocally aligned optical excitation and ultrasonic detection,limiting the wide-field imaging speed of these systems.Although several multifocal OR-PA(MFOR-PA)systems have attempted to address this limitation,they are hindered by the complex design in a constrained physical space.Here,we present a two-dimensional(2D)MFOR-PAM system that utilizes a 2D microlens array and an acoustic ergodic relay.Using a single-element ultrasonic transducer,this system can detect PA signals generated from 400 optical foci in parallel and then raster scan the optical foci patterns to form an MFOR-PAM image.This system improves the imaging resolution of an acoustic ergodic relay system from 220 to 13μm and enables 400-folds shorter scanning time than that of a conventional OR-PAM system at the same resolution and laser repetition rate.We demonstrated the imaging ability of the system with both in vitro and in vivo experiments.