A system for converting a vertical optical microscope unit to provide selective plane illumination microscopy includes an illumination source unit configured to generate a light sheet along a longitudinal axis to illuminate a sample placed in a vertical optical detection axis of the vertical optical microscope unit. The illumination source unit is configured to generate the light sheet along the longitudinal axis that is substantially perpendicular to the vertical optical detection axis of the vertical optical microscope unit. The illumination source unit is configured to produce an excitation at a plane in the sample that generates fluorescent emissions. A detection sensor is placed in a detection optical path of the vertical optical detection axis of the vertical optical microscope unit. The detection sensor is configured to detect the fluorescent emissions to provide selective plane illumination microscopy.