Reflectance confocal microscopy (RCM) has become a standard method for skin diagnostics. It is based on tightly focusinga continuous laser beam with an objective into the skin and collecting the back scattered light through a pinhole forgenerating images of selected planes to a depth of several 100 micrometers. For enhancing its diagnostic capability, theRCM can be combined with optical resolution photoacoustic microscopy (OR-PAM), providing strong optical absorptioncontrast for melanocytic lesions. We have developed a compact add-on to common optical objectives that is able to detectthe photoacoustically generated transients with high bandwidth, using four piezoelectric elements made of poly-vinylidenefluoride (PVDF). The elements are arranged on four quadrants of a conical surface around the objective, taking advantageof the focusing effect of the slightly curved surface. For taking an image, the pulsed and continuous excitation beams aresimultaneously scanned over the sample using a pair of galvanometric mirrors. Photoacoustic images of the selected planeare then generated for each separate sensing element and are subsequently added in order to achieve an enhanced signalto-noise ratio. Simultaneously recorded back scattered light provides the input for the RCM mode. We present acharacterization of the sensors and provide experimental results on phantoms.
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