Living specimens, particularly developing embryos, are often sensitive to light exposure. Light sheet microscopy – also referred to as single plane illumination microscopy or SPIM – is a gentle way of imaging sensitive samples or fast biological processes in vivo. The specimen is illuminated only in a single plane at a time and detected from the perpendicular direction. Since there is no out-of-focus excitation, phototoxic effects are reduced to the focal plane. Light sheet imaging has intrinsic optical sectioning. By moving the sample through the light sheet, 3D images of a specimen can be recorded.