Autofocusing optical-resolution photoacoustic microscopy

Area of Science:

• Biomedical Imaging
• Optical Microscopy
• Photoacoustics

Background:

• Optical-resolution photoacoustic microscopy (OR-PAM) offers high resolution but relies on precise focusing.
• Current manual focusing methods are operator-dependent, imprecise, and time-consuming, limiting OR-PAM's practical use.

Purpose of the Study:

• To develop an automated focusing system for OR-PAM to overcome limitations of manual focusing.
• To improve the precision, speed, and reliability of OR-PAM focusing.

Main Methods:

• Developed an autofocusing optical-resolution photoacoustic microscopy (AFOR-PAM) system.
• Integrated 3D motorized scanning, System-on-Chip (SoC) for unified control, and a modified Brenner gradient autofocusing algorithm.

Main Results:

• The AFOR-PAM system achieved automated focusing in 11 iterations and 1.4 seconds.
• Demonstrated rapid, precise, and reliable focusing in phantom and in vivo (mouse ear) experiments.
• Showcased robustness under low signal-to-noise ratio (SNR) conditions.

Conclusions:

• The AFOR-PAM system provides a fully automated, operator-independent focusing solution.
• This advancement significantly enhances the practical applicability of OR-PAM.
• The system holds potential for broader use in clinical photoacoustic imaging settings.