ZERODUR® and Optical Glass in High-Stress Applications

Author(s): Peter Hartmann

Published: 2024

PDF ISBN: 9781510679900 | Print ISBN: 9781510679894

DESCRIPTION

Brittle materials such as ZERODUR® and optical glass, which are crucial in enabling the key functions of optical systems, break due to surface tensile stress depending on their surface condition. This book shows that for each surface condition, a certain stress limit exists below which no breakage occurs. The growth law for subsurface micro-cracks that are the cause of breakage allows one to calculate the admissible stress for the intended lifetime of the optical system, including environmental fatigue.

This book presents a breakage stress measurement method and a comprehensive number of results for ZERODUR® with various surface conditions in practical use and for determining the fatigue dominating stress corrosion. A verification test confirms the validity of the lifetime prediction model. Breakage stress results are also given for a selection of optical glass types. To estimate the threshold breakage stresses for glass types for which these stresses cannot be measured, correlations with other physical quantities such as Knoop hardness and fracture toughness are investigated. Recommendations are given for improving strength in design and operation. A set of well-known applications of ZERODUR® in astronomy proves the suitability of glass and glass ceramic materials under mechanical stress loads.

"This is a brilliant book that the ZERODUR and optical glass community has needed for many years. I believe that Peter Hartmann’s deep knowledge and insight into the mechanical strength of glass surfaces will have a significant and permanent impact on the optics manufacturing community."
– John Lambropoulos, Professor, University of Rochester