Optical-resolution photoacoustic microscopy by use of a multimode fiber

We demonstrate Optical-Resolution Photoacoustic Microscopy (OR-PAM), where the optical field is focused and scanned using Digital Phase Conjugation through a multimode fiber. The focus is scanned across the field of view using digital means, and the acoustic signal induced is collected by a transducer. Optical-resolution photoacoustic images of a knot made by two absorptive wires are obtained and we report on resolution smaller than 1.5 mu m across a 201 mu m x 201 mu m field of view. The use of a multimode optical fiber for the optical excitation part can pave the way for miniature endoscopes that can provide optical-resolution photoacoustic images at large optical depth. (C) 2013 AIP Publishing LLC.