Another instrument used to measure disk media is the OptiFLAT substrate tester

Another instrument used to measure disk media is the OptiFLAT substrate tester from ADE Phase Shift. Using white light, the tool measures the front-surface flatness of plane-parallel transparent substrates without coating the rear surface. The OptiFLAT features fully interactive data mapping, bearing-surface analysis, and data manipulation; uploading of statistics to networks; single-pass flatness and microwaviness data gathering; high-resolution CCD camera; and video alignment for tip/tilt and distance adjustment.