Parallel multifocus optical-resolution photoacoustic microscopy based on tunable acoustic gradient lens and fiber delay network

We developed a multifocus optical-resolution photoacoustic microscope (MPAM) with extended depth of field (DoF) by using a tunable acoustic gradient (TAG) lens and a pulse delay method. TAG lens is designed to control the divergence angle of the laser beam. Three fibers with different length are used to output three laser pulses with different delay time. By controlling the fire time of the laser pulses, we can get three focal spot through TAG lens in our system in one A-line data acquisition. The DoF of MPAM measured using a vertically tilted carbon fiber is about 775 micrometers. The lateral resolution is estimated to be 2.8 micrometers. A phantom consists of tungsten wires and a zebrafish is used to verify the large depth-of-field of our system.