Advancing photoacoustic microscopy via single-source triple-beam interference excitation

Area of Science:

• Biomedical optics
• Microscopy techniques
• Acoustic imaging

Background:

• Conventional focused Gaussian beam excitation in photoacoustic microscopy (PAM) limits detection visibility and spatial resolution.
• Increasing optical numerical aperture (NA) improves resolution but reduces working distance (WD) and depth of field (DoF), hindering large-volume imaging.
• A fundamental trade-off exists between optical resolution and ultrasonic penetration in PAM.

Purpose of the Study:

• To introduce a triple-beam interference excitation strategy for enhanced PAM performance.
• To overcome the limitations of conventional Gaussian beam excitation in PAM.
• To preserve extended working distances and depths of field in high-resolution PAM.

Main Methods:

• Utilizing precise angular modulation of triple coherent excitation beams from a single source.
• Optimizing interference fringe patterns to disrupt destructive interference of photoacoustic signals.
• Implementing a five-step phase-shifting algorithm on the interference pattern.

Main Results:

• Achieved a sixfold enhancement in axial detection visibility compared to Gaussian beam-based PAM.
• Demonstrated two- to threefold improvements in lateral and axial resolution beyond diffraction limits.
• Validated the methodology through theoretical modeling and experimental imaging of phantoms and biological specimens.

Conclusions:

• The proposed triple-beam interference strategy significantly enhances PAM performance.
• This method effectively addresses the trade-off between resolution and imaging depth in PAM.
• The technique offers a promising approach for advanced biomedical imaging applications.