Zerodur

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Zerodur (notation of the manufacturer: ZERODUR®), a registered trademark of Schott AG,[1] is a lithium aluminosilicate glass-ceramic[2] produced by Schott AG since 1968.[3] It has been used for a number of very large telescope mirrors including Keck I, Keck II,[4] and SOFIA. With its very low coefficient of thermal expansion it can be used to produce mirrors which retain acceptable figures in extremely cold environments such as deep space.[5] Although it has advantages for applications requiring a coefficient of thermal expansion less than that of borosilicate glass it remains very expensive as compared to borosilicate. The tight tolerance on CTE ± 0.007 x 10−7/K allows for highly accurate applications which require high-precision.

Zerodur has both an amorphous (vitreous) component and a crystalline component. Its most important properties[6] are:

Applications[edit]

The Keck II Telescope showing the segmented primary mirror made of Zerodur
  1. Optics
  2. Microlithography
  3. Measurement technology[3]

Properties[6][edit]

See also[edit]

References[edit]

  1. ^ http://www.unitedlens.com/page175.html
  2. ^ a b Viens, Michael J (April 1990). "Fracture Toughness and Crack Growth of Zerodur" (PDF). NASA Technical Memorandum 4185. NASA. Retrieved 28 August 2011. 
  3. ^ a b Schott AG Zerodur description
  4. ^ Döhring, Thorsten; Peter Hartmann, Ralf Jedamzik, Armin Thomas, Frank-Thomas Lentes. "Properties of Zerodur Mirror Blanks for Extremely Large Telescopes" (PDF). Proc. of SPIE Vol. 6148 61480G-8. SPIE. Retrieved 26 August 2011. 
  5. ^ Baer, JW; WP Lotz. "Figure testing of 300 mm Zerodur mirrors at cryogenic temperatures" (PDF). Retrieved 26 August 2011. 
  6. ^ a b Schott AG Zerodur properties
  7. ^ SCHOTT CTE Grades
  8. ^ Hartmann, P. (18 December 2012). "ZERODUR - Deterministic Approach for Strength Design" (PDF). NASA. Retrieved 11 September 2013. 
  9. ^ Senf, H; E Strassburger; H Rothenhausler (1997). "A study of Damage during Impact in Zerodur". J Phys Iv France (in English) 7 (Colloque C3, Suppltment au Journal de Physique I11 d'aotit 1997). Retrieved 31 August 2011. 

External links[edit]