Zerodur
Zerodur is a lithium-aluminosilicate glass-ceramic manufactured by Schott AG. Zerodur has a near zero coefficient of thermal expansion (CTE), and is used for high-precision applications in telescope optics, microlithography machines and inertial navigation systems.
Applications
[edit]
The main applications for Zerodur include telescope optics in astronomy[2] and space applications,[3] lithography machines for microchips and displays,[4] and inertial measurements systems for navigation.[5][6]
In astronomy, it is used for mirror substrates in large telescopes such as the Hobby-Eberly Telescope,[7] the Keck I and Keck II telescopes,[8] the Gran Telescopio Canarias,[9] the Devasthal Optical Telescope,[10] the European Southern Observatory's 8.2 m Very Large Telescope,[11] and the 39 m Extremely Large Telescope.[12] It also has been used for the primary mirror of SOFIA's airborne telescope.[13]
In space, it has been used for the imager in Meteosat Earth observation satellites,[14] and for the optical bench in the LISA Pathfinder mission.[15]
In microlithography, Zerodur is used in wafer steppers and scanner machines for precise and reproducible wafer positioning.[16][17] It is also used as a component in refractive optics for photolithography.[18]
In inertial measurement units, Zerodur is used in ring laser gyroscopes.[19]
Properties
[edit]Zerodur has both an amorphous (vitreous) component and a crystalline component. Its most important properties[20] are:
- The material exhibits a particularly low thermal expansion, with a mean value of 0 ± 0.007×10−6 K−1 within the temperature range of 0 to 50 °C.[21]
- High 3D homogeneity[21] with few inclusions, bubbles and internal stria.
- Hardness similar to that of borosilicate glass.
- High affinity for coatings.
- Low helium permeability.
- Non-porous.
- Good chemical stability.
- Fracture toughness approximately 0.9 MPa·m1/2.[22][23]
Physical properties
[edit]- Dispersion: (nF − nC) = 0.00967
- Density: 2.53 g/cm3 at 25 °C
- Young's modulus: 9.1×1010 Pa
- Poisson ratio: 0.24
- Specific heat capacity at 25 °C: 0.196 cal/(g·K) = 0.82 J/(g·K)
- Coefficient of thermal expansion (20 °C to 300 °C) : 0.05 ± 0.10×10−6/K
- Thermal conductivity: at 20 °C: 1.46 W/(m·K)
- Maximum application temperature: 600 °C
- Impact resistance behavior is substantially similar to other glass[24]
History
[edit]Schott began developing glass-ceramics in the 1960s lead by Jürgen Petzoldt, in response to demand for low expansion glass ceramics for telescopes.[25]
In 1966, Hans Elsässer, the founding director of the Max Planck Institute for Astronomy (MPIA), asked the company if it could produce large castings of almost 4 meters using low-expansion glass-ceramic for telescope mirror substrates. In 1969, the MPIA ordered a 3.6 m (12 ft) mirror blank, along with ten smaller mirror substrates. The mirrors were delivered by late 1975,[25] and went into operation in 1984 in a telescope at the Calar Alto Observatory in Spain. Further orders for mirror blanks followed.[26]
See also
[edit]References
[edit]- ^ "Secondary Mirror of ELT Successfully Cast - Largest convex mirror blank ever created". www.eso.org. Retrieved 22 May 2017.
- ^ Döhring, Thorsten (May 2019). "Four decades of ZERODUR mirror substrates for astronomy". In Jiang, Wenhan; Geyl, Roland; Cho, Myung K.; Wu, Fan (eds.). 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes. Proceedings of the SPIE. Vol. 7281. doi:10.1117/12.831423. Retrieved 10 May 2024.
- ^ Carré, Antoine (May 2023). "Comprehensive review of the effects of ionizing radiations on the ZERODUR® glass ceramic". Journal of Astronomical Telescopes, Instruments, and Systems. 9 (2). doi:10.1117/1.JATIS.9.2.024005.
- ^ "SCHOTT Strengthens Glass Substrate Portfolio". Printed Electronics Now. September 29, 2023.
- ^ Sokach, Stephen (July 2020). "ZERODUR: The Highly Technical Glass-Ceramic". Tech Briefs. Retrieved 10 May 2024.
- ^ "Zerodur". Mindrum Precision. Retrieved 10 May 2024.
- ^ "Hobby-Eberly Telescope | McDonald Observatory". mcdonaldobservatory.org. Retrieved 2024-07-12.
- ^ "A Mirror's Perfect Reflection". W.M. Keck Observatory. 28 May 2010. Retrieved 10 May 2024.
- ^ "Description of the GTC". Gran Telescopio CANARIAS. Retrieved 10 May 2024.
- ^ "3.6 m DOT Telescope". ARIES. Retrieved July 7, 2024.
- ^ "Very Large Telescope". ESO. Retrieved 10 May 2024.
- ^ "Mirrors and Optical Design". ESO. Retrieved 10 May 2024.
- ^ Krabbe, Alfred (June 2000). Melugin, Ramsey K.; Roeser, Hans-Peter (eds.). "SOFIA telescope". Proceedings, Airborne Telescope Systems. Airborne Telescope Systems. 4014: 276. arXiv:astro-ph/0004253. Bibcode:2000SPIE.4014..276K. doi:10.1117/12.389103. Retrieved 10 May 2024.
- ^ "MTG (Meteosat Third Generation) - eoPortal". www.eoportal.org. Retrieved 2024-07-12.
- ^ "LISA Technology Package Optical Bench Interferometer During Calibration". ESA. Retrieved 10 May 2024.
- ^ Hartmann, Peter. "SCHOTT – Ultra low expansion glass ceramic ZERODUR" (PDF). Max-Planck-Institut für Astronomie. p. 49. Retrieved 10 May 2024.
- ^ Jedamzik, Ralf (2014). "Glass ceramic ZERODUR enabling nanometer precision". In Lai, Kafai; Erdmann, Andreas (eds.). Optical Microlithography XXVII. Proceedings of the SPIE. Vol. 9052. pp. 90522I. Bibcode:2014SPIE.9052E..2IJ. doi:10.1117/12.2046352.
- ^ Mitra, Ina (September 2022). "ZERODUR: a glass-ceramic material enabling optical technologies". Optical Materials Express. 12 (9): 3563. doi:10.1364/OME.460265. Retrieved 10 May 2024.
- ^ Pinckney, Linda R. (2003). "Glass-Ceramics". Encyclopedia of Physical Science and Technology (Third Edition): 807–816. doi:10.1016/B0-12-227410-5/00293-3. ISBN 978-0-12-227410-7. Retrieved 10 May 2024.
- ^ "Technical Details ZERODUR®". schott.com. Retrieved 6 September 2024.
- ^ a b Hartmann, Peter; Jedamzik, Ralf; Carré, Antoine; Krieg, Janina; Westerhoff, Thomas (24 March 2006). "Glass ceramic ZERODUR®: Even closer to zero thermal expansion: a review, part 2". Journal of Astronomical Telescopes, Instruments, and Systems. 7 (2). doi:10.1117/1.JATIS.7.2.020902.
- ^ Viens, Michael J (April 1990). "Fracture Toughness and Crack Growth of Zerodur". NASA Technical Memorandum 4185. NASA. Retrieved 6 September 2024.
- ^ Hartmann, P. (18 December 2012). "ZERODUR - Deterministic Approach for Strength Design" (PDF). Optical Engineering. 51 (12). NASA: 124002. Bibcode:2012OptEn..51l4002H. doi:10.1117/1.OE.51.12.124002. S2CID 120843972. Retrieved 11 September 2013.
- ^ Senf, H; E Strassburger; H Rothenhausler (1997). "A study of Damage during Impact in Zerodur" (PDF). J Phys IV France. 7 (Colloque C3, Suppltment au Journal de Physique I11 d'aotit 1997): C3-1015-C3-1020. doi:10.1051/jp4:19973171. Retrieved 31 August 2011.
- ^ a b Pannhorst, Wolfgang (1995). "Chapter 4: Zerodur® - A Low Thermal Expansion Glass Ceramic for Optical Precision Applications". In Bach, Hans (ed.). Low Thermal Expansion Glass Ceramics. Springer. pp. 107–121. ISBN 3-540-58598-2.
- ^ Lemke, Dietrich. Im Himmel über Heidelberg - 50 Jahre Max-Planck-Institut für Astronomie in Heidelberg (1969 – 2019) (PDF) (in German). Berlin, Heidelberg.