Vibrational photoacoustic microscopy for depth-resolved bond-selective imaging of tissues and organisms

We realize vibrational photoacoustic microscopy (VPA) using molecular excitation of overtone vibration and acoustic detection of the resultant pressure transients. We demonstrate 3-D VPA imaging of lipid-rich atherosclerotic plaques and lipid bodies in living Drosophila larvae by exciting 2
^nd
overtone of the CH bond stretch around 8300 cm
⁻¹
. Depth-resolved spectral analysis and a penetration depth of several mm are available.