Multifocus optical-resolution photoacoustic microscope using ultrafast axial scanning of single laser pulse

Abstract

A tunable acoustic gradient (TAG) lens has been introduced in the fast axial scanning in optical imaging. However, it still needs additional imaging time for depth scanning. In this study, we split a single laser pulse into three sub-pulses and introduce them into three fibers with different lengths. The sub-pulses out of the fibers were combined thereafter. We then obtained a pulse train with a time interval of 120 ns. By controlling the fire time of the pulse train and the driving signal of the TAG lens, we can receive three focal spots in one A line data acquisition using a single input laser pulse. The depth of focus (DoF) of the system was measured to be 360 μm, which is three times of that of previous systems without the sacrifice of time resolution. A mouse ear and mouse cerebral vasculature were imaged in-vivo to demonstrate the feasibility of the extended DoF of our system.