Profile: Esco Optics is a manufacturer of optics, and precision optical components. Optical flats are most commonly used as test plates to evaluate the accuracy of unknown optical surfaces. We manufacture optical flats out of G1 grade fused quartz with low thermal expansion, abrasion resistance and general stability of this material allows continuous use with minimal degradation over time. We offer optical flats with either one or two precision surfaces. We can test flat optical surfaces by holding the precision of an optical flat against the test surface. We manufacture a wide variety of flat mirror substrates. Our catalog mirrors are supplied front surface-coated with aluminum (Al) and are over-coated with either silicon monoxide (SiO) or magnesium fluoride (MgF2). We offer an extensive list of shapes, including concave and convex spherical, ellipsoidal, flat, square, round, or custom.