Multiscale photoacoustic microscopy with continuously tunable resolution.

A multiscale photoacoustic microscope with continuously tunable lateral resolution is developed. The tunable resolution is achieved by using an electrical varifocal lens and an optical fiber bundle. The varifocal lens is used to generate a size tunable focused laser spot on the tip of the fiber bundle. Laser beams emerging from the other end of the fiber bundle are imaged into the object as the excitation light spot for acoustic generation. The verified lateral resolution of the system can be tuned from ~1  μm to more than 44.8 μm, which span from optical resolution to acoustic resolution. Additionally, a mouse ear was imaged in vivo using three different resolutions to demonstrate the feasibility of the multiscale imaging capability of our system.