Corning Tropel Corp.'s UltraFlat 200 mask system measures the flatness of polished photomasks, coated or uncoated. The system uses near-normal-incidence interferometry and proprietary phase-shifting analysis software to deliver 50-nm measurement uncertainty. It measures photomasks of up to 6 in. on both sides. The company says that the system, which operates under Windows 2000's menu-driven software, provides measurements on a high-resolution color monitor in less than 30 s. The measurements are NIST-traceable and meet SEMI standards.