Interference-Corrected Synthetic Aperture Focusing Technique for Photoacoustic Microscopy

We report an adaptive interference-corrected synthetic aperture focusing technique (IntC-SAFT) for improving the imaging performance of photoacoustic microscopy (PAM) in terms of depth-of-field (DOF), spatial resolution (both axial and lateral), and signal-to-noise-ratio (SNR). Even though conventional synthetic aperture focusing technique (SAFT) takes into account coherency and proper time delays of the boundary measured (time-resolved) photoacoustic (PA) signals while undertaking reconstruction procedure, it does not follow or violates the wave theory of interference. Our proposed beam-forming-based reconstruction algorithm takes into account of interference effect that introduces an additional interference term in SAFT, i.e., our proposed algorithm takes due consideration of coupling effect while undertaking summing-up of interfering (PA) waves. Experimental validation studies were performed in tissue-mimicking (Agar) phantoms, chicken breast tissues, and leaf veins. Results demonstrated that our proposed IntC-SAFT outperforms conventional SAFT improving SNR (up to
$\sim \!88\%$
), contrast ratio (up to
$\sim \!170\%$
), axial resolution (up to
$\sim \!26\%$
), and lateral resolution (up to
$\sim \!53\%$
).