Sapphire and single-crystal quartz cell windows for Beckman and other centrifuges are available from Meller Optics Inc. The windows are made from sapphire to resist chemicals and scratching and to withstand high pressure. The single-crystal quartz types are for less demanding applications. Measuring 19.03 ±0.03 mm in diameter and 0.5 mm ±0.10 mm thick, the ultraviolet cell windows are scribed on their edges with the projection of the optic axis to simplify alignment. Suitable for OEM and replacement applications, they are available wedged 1º or 2º and plano, with chamfers 0.20/0 mm/0.50 mm x 45º in two places. Surface finishes are 30-5 scratch-dig for sapphire windows and 10-5 for single-crystal quartz, within a central clear aperture of 16 mm.