The flatness and roughness of nine common substrate materials (quartz flat, Corning 7059 glass, Corning 0211 glass, soft glass, AlSiMag 614, AlSiMag 614 with 743 glaze, AlSiMag 772, mechanically polished silicon, and chemically polished silicon) are reported. Corning 0211 and the three alumina samples had a flatness on the order of 1 part/thousand. Corning 7059, soft glass, and both silicon samples had a flatness on the order of 0.1 part/thousand. The quartz flat had a flatness on the order of 2×10−3 part/thousand. AlSiMag 614 and 772 exhibited a roughness of 10 000 and 5000 Å average peak to peak, respectively. Chemically polished silicon exhibited a roughness of ∼300 Å. The quartz flat, Corning 7059 glass, Corning 0211 glass, soft glass, AlSiMag 614 with 743 glaze, and the mechanically polished silicon all exhibited a roughness on the order of or below the resolution limit (∼50 Å) of the measuring instrument.