The DSU (Disc Scanning Unit) offers cost efficient semi-confocal image observation with a cooled CCD camera and an arc lamp illumination source. The DSU disc contains a pattern of slits that creates a virtual pinhole as the disc spins at 3000 rpm. It removes out of focus blur, thereby enhancing resolution. This yields clear, continuous, optically cross-sectioned images. The DSU is compatible with both inverted and upright Olympus microscopes, including the motorised IX81 and BX61 making it especially suitable for automated Z-sectioning followed by post image processing like 3D reconstruction. The water-immersion BX61WI and BX51WI electrophysiology microscopes and the entire line of water immersion objectives are also supported.