The 950B, usually referred to as the “scanner” is configured for 6 inch wafers. It has a numerical aperture of 0.63. Its light source is a Cymer ArF 10W Excimer Laser that generates light at 193 nm wavelength. It utilizes fused silica reticles that are 6 inches square and 0.250 inches thick. It can print a 26 mm by 32 mm field in one flash. Specified resolution is 130 nm, but smaller dimensions can be achieved in research mode. It has an Aerial II illumination system that is usually operated in annular mode, but it is capable of conventional illumination.