A photoacoustic microscope system provides label-free multilayered histology-like imaging of unprocessed human breast specimens.

Compared with visible light (380–700 nm), near-infrared light (700–1400 nm) undergoes weaker optical attenuation in biological tissue, thus it can penetrate deeper. Here, we demonstrate near-infrared optical-resolution photoacoustic microscopy (NIR-OR-PAM) with 1046 nm illumination. A penetration depth of 3.2 mm was achieved in chicken breast tissue ex vivo using optical fluence within the ANSI limit (100 mJ/cm2). Beyond ~0.6 mm deep in chicken breast tissue, NIR-OR-PAM has shown finer resolution than the visible counterpart with 570 nm illumination. The deep imaging capability of NIR-OR-PAM was validated in both the mouse ear and mouse brain. NIR-OR-PAM of possible lipid contrast was explored as well.

No abstract