Cross-optical-beam nonlinear photoacoustic microscopy

We present a photoacoustic microscopy (PAM) technique with an optical sectioning capability. By combining crossoptical- beam illumination with nonlinear PAM, an axial resolution of 8.7 μm was measured, demonstrating a fourfold improvement over the acoustically determined value. Compared to methods relying on high-frequency ultrasound transducers to improve the axial resolution, our approach offers a greater working distance and a higher signal-to-noise ratio.