Zerodur - Glass Ceramic for Telescope Mirrors

Zerodur® is a glass ceramic featuring extremely low expansion on exposure to changing temperature. The material is relatively hard and should be treated with a special polish. Zerodur, a registered trademark of Schott AG, is a glass ceramic. Used in large, professional telescopes, it is the material of choice for mirrors. What makes Zerodur® special is that it features extremely low expansion on exposure to changing temperature. The material is relatively hard and should be treated with a special polish. Zerodur® has to be handled gently as far as cementing is concerned – at temperatures above 100 °C, it loses its zero expansion.