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

• Published in: Light, science & applications science & applications, 2020-07, Vol.9 (1), p.135-135, Article 135
• Main Authors: Li, Yang, Wong, Terence T. W., Shi, Junhui, Hsu, Hsun-Chia, Wang, Lihong V.
• Format: Article
• Language: English
• Subjects: 639/624/1107/328; 639/624/1107/510; Applied and Technical Physics; Atomic; Classical and Continuum Physics; Lasers; Letter; Microscopes; Microscopy; Molecular; Optical and Plasma Physics; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; Scanning; Ultrasonic transducers
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-020-00372-x

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 13 μm 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.