ZERODUR and optical glass in high-stress applications /
The extremely low expansion glass ceramic ZERODUR and optical glass are crucial materials enabling the key functions of optical systems. In some of their applications they are subject to mechanical forces, which lead to bending stress loads. For the intended functions it is essential that the optica...
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| Format: | Book |
| Language: | English |
| Published: |
Bellingham, Washington :
SPIE,
[2024].
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| Series: | SPIE Press monograph ;
PM378. |
| Subjects: |
| Summary: | The extremely low expansion glass ceramic ZERODUR and optical glass are crucial materials enabling the key functions of optical systems. In some of their applications they are subject to mechanical forces, which lead to bending stress loads. For the intended functions it is essential that the optical elements remain undamaged throughout their total lifetime. Brittle materials such as ZERODUR and optical glass break due to surface tensile stress depending on their surface condition. It is shown that for each surface condition a certain stress limit exists below which no breakage occurs. The breakage stress probability is described using the three parameter Weibull distribution. The parameter threshold breakage stress defines the allowable stress for given optical element designs. The underlying cause for breakage is the presence of subsurface micro cracks. The growth law for the micro cracks allows taking fatigue into account and so to calculate the admissible stress for the intended lifetime of the optical system. The experimental part comprises the presentation of the breakage stress measurement method and a comprehensive number of results for ZERODUR with different surface conditions such as ground with diamond grains, lapped with silicon carbide grains, etched and polished and for the determination of the fatigue dominating stress corrosion. A verification test confirmed 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 the many other glass types, which could not be measured, correlations with other physical quantities such as Knoop hardness and fracture toughness have been 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 the glass and glass ceramic materials under mechanical stress loads. |
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| Physical Description: | xix, 203 pages : illustrations (some color) ; 26 cm. |
| Bibliography: | Includes bibliographical references and index. |
| ISBN: | 9781510679894 1510679898 |