Near-infrared double-illumination optical-resolution photoacoustic microscopy

Label-free chemical bond imaging is of great importance in biology and medicine. Photoacoustic imaging at the third near-infrared windows (1600-1870 nm, nearinfrared-III) provides a stable molecular vibrational imaging tool for lipid-rich tissue owing to the first overtone transition of the C-H bond at 1.7 _m. However, lacking high-energy pulsed laser sources at 1.7 _m and the strong water absorption significantly limit the signal-to-noise ratio of the lipid imaging, especially for thin lipid tissues. To circumvent this barrier, we develop near-infrared-III double-illumination optical-resolution photoacoustic microscopy (DIOR-PAM) for improving the sensitivity of label-free lipid imaging. Using the same laser, DIOR-PAM can enhance the sensitivity by nearly 100%, which we prove in the Monte Carlo simulation.We experimentally demonstrated 50%i100% sensitivity enhancement on non-biological and biological lipid-rich samples. This article is protected by copyright. All rights reserved.