PROVIDENCE, R.I., Dec. 7, 2010 — Custom engineered sapphire windows that can operate from full vacuum to 10,000 psi, depending upon the configuration, and from cryogenic to 1000 °C while resisting chemicals and particulates are available from Meller Optics Inc. The Sapphire Viewport windows are manufactured to specification in sizes from¼- to 10-in. in diameter and from ½ mm to 1 in. thick, with stepped edges and elliptical edge shaping, holes, slots and wedges for mounting, and antireflection coatings. Featuring Moh 9 hardness, they are resistant to chemicals (fluorine to 300 °C) and most acids, and are impervious to water, and blowing dirt and sand. They are second only to diamond in terms of hardness. Precision fabricated, they exhibit flatness to 0.5 fringes HeNe and parallelism from 20 to 2 arcsec. They are priced according to configuration, size and quantity, and price quotations and complete material specifications are available upon request.