Optical-resolution photoacoustic microscopy with a needle-shaped beam

Area of Science:

• Biomedical Optics
• Microscopy
• Photoacoustics

Background:

• Optical-resolution photoacoustic microscopy (OR-PAM) offers cellular-level visualization of optical absorption.
• Limited depth of field (DOF) in OR-PAM restricts high-resolution imaging of uneven surfaces and volumetric data acquisition.

Purpose of the Study:

• To overcome the depth of field limitation in OR-PAM.
• To introduce needle-shaped beam photoacoustic microscopy (NB-PAM) for enhanced imaging.
• To demonstrate NB-PAM's capability for slide-free and in vivo imaging.

Main Methods:

• Development of customized diffractive optical elements (DOEs) to generate a needle-shaped beam.
• Utilizing the needle beam to achieve an extended DOF (~28-fold Rayleigh lengths).
• Application of NB-PAM with 266 nm and 532 nm lasers for distinct imaging tasks.

Main Results:

• NB-PAM successfully extended the DOF while maintaining beam quality (uniform intensity, minimal sidelobes).
• Histology-like imaging of fresh, slide-free organs was achieved.
• High-resolution in vivo imaging of mouse brain vasculature was demonstrated.

Conclusions:

• NB-PAM overcomes the DOF limitations of conventional OR-PAM.
• The technology facilitates high-quality, slide-free pathological imaging and in vivo organ imaging.
• NB-PAM offers significant potential for intraoperative diagnostics and preclinical research.