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

Yang Li; Terence T W Wong; Junhui Shi; Hsun-Chia Hsu; Lihong V Wang

doi:10.1038/s41377-020-00372-x

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

Light Sci Appl. 2020 Jul 31:9:135. doi: 10.1038/s41377-020-00372-x. eCollection 2020.

Authors

Yang Li^{1

2}, Terence T W Wong^{1

2

3}, Junhui Shi¹, Hsun-Chia Hsu^{1

2}, Lihong V Wang¹

Affiliations

¹ Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 USA.
² Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899 USA.
³ Present Address: Translational and Advanced Bioimaging Laboratory, Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Hong Kong, China.

Abstract

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.

Keywords: Imaging and sensing; Microscopy.

Abstract

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