In vivo dark-field reflection-mode photoacoustic microscopy

TLDR

The study presents a reflection‑mode photoacoustic microscopy system designed for noninvasive in vivo imaging of skin blood vessels. The system uses dark‑field laser illumination with a high‑numerical‑aperture acoustic lens and broadband ultrasonic detection in a coaxial confocal configuration, achieving lateral resolution of 45–120 µm and axial resolution of ~15 µm. The system successfully images optical‑absorption contrast up to 3 mm deep in biological tissue.

Abstract

Reflection-mode photoacoustic microscopy with dark-field laser pulse illumination and high-numerical-aperture ultrasonic detection is designed and implemented in noninvasively imaged blood vessels in the skin in vivo. Dark-field optical illumination minimizes the interference caused by strong photoacoustic signals from superficial structures. A high-numerical-aperture acoustic lens provides high lateral resolution, 45–120?m in this system. A broadband ultrasonic detection system provides high axial resolution, estimated to be ?15?m. The optical illumination and ultrasonic detection are in a coaxial confocal configuration for optimal image quality. The system is capable of imaging optical-absorption contrast as deep as 3mm in biological tissue.