High-resolution epi-illumination raster-scan optoacoustic mesoscopy for imaging of model organisms and microvessels.

We have developed an epi-illumination raster-scan optoacoustic mesoscopy system (RSOM), the new system is capable of imaging model organisms, and vasculature. The newly developed system is based on a custom designed; spherically focused detector with a Characterization of the system shows an isotropic lateral resolution of 18 μm, and an axial resolution of 4 μm. The scan times are on the order of 8 minutes for a field of view of 10×10 mm2. The achieved resolution is slightly degraded up to a depth of 5 mm. After characterizing the system we showcase it's performance on a zebrafish ex vivo, and an excised mouse ear. Additionally, to improve the visibility of small structures we have reconstructed the high frequencies, and the low frequencies separately, and at the end overplayed the two reconstructions using different colors, this way the high frequencies are not masked by the low frequencies which have a higher signal to noise ratio