The Olympus DSU (Disk Scanning Unit) represents a breakthrough in spinning disk confocal technology. Designed by Olympus, the DSU disk contains a pattern of slits that creates a virtual pinhole as the disk spins at 3,000 rpm. Designed to optimize the tradeoff between confocality and light throughput, the DSU uses an arc lamp illumination source for maximum excitation wavelength flexibility at a reasonable cost. The DSU is compatible with both inverted and upright Olympus microscopes, including the motorized IX81 and BX61 making it an ideal imaging system for automated Z-stack, 3-D image analysis. The water-immersion BX61WI and BX51WI electrophysiology microscopes and the entire water immersion objective line are also supported, which allows an optimum configuration for in-vivo applications in zoology and cytology.