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SCHOTT now offers ZERODUR®, a glass-ceramic optimized for minimal response to thermal perturbations, in monolithic 4-meter diameters in highly lightweighted forms, important for the larger mirrors used in space telescopes.
International technology group SCHOTT will showcase a lightweighted 1.2-meter ZERODUR® mirror at SPIE Optics and Photonics in San Diego on August 6-10, 2017. Last year, this mirror underwent thermal-vacuum tests by NASA at the Marshall Space Flight Center, validating the excellent thermal suitability of ZERODUR® for use in space-based telescopes.
“Though we like to think of space as incredibly cold, the temperature does change,” said Tony Hull Consultant to SCHOTT. “When a satellite passes through the shadow of the moon, or when its mirrors are pointed at the sun, space telescopes go through thermal changes that can cause a slight expansion or contraction that could distort the imagery.”
Space telescope architecture is driven by resistance to thermal changes. Decades of testing prove ZERODUR® low-expansion glass-ceramic is an ideal choice for astronomical applications because of its low coefficient of thermal expansion.
Advances in astronomy are leading to the desire for bigger and bigger telescopes. Among the presently preferred materials for space, only SCHOTT can currently provide monolithic mirrors in sizes larger than 1.5 meters in diameter. Competitive materials presently need to be fabricated out of several pieces using fusing, bonding, or brazing techniques.
Larger mirrors, however, typically mean more weight. Not with ZERODUR®. SCHOTT now has assets to offer monolithic 4-meter diameter mirror blanks providing stiffness, but with 85 to 90 percent of the mass removed, while efficiently maintaining structural integrity crucial factors in the selection of material for travel to space.
The use of ZERODUR® in space is not new. Over the past several decades, ZERODUR® has flown successfully on over 30 space missions, including the Chandra X-Ray Observatory, the secondary mirror of the Hubble Space Telescope, and both NASA Great Observatories.
In addition to space-based telescopes, ZERODUR® has been used in many terrestrial telescopes. SCHOTT recently produced a 4.3-meter blank for the Daniel K. Inouye Solar Telescope. It has also been called upon four times to produce mirror substrates for the European Extremely Large Telescope (ELT). The primary mirror consisting of 798 1.4-meter point to point hexagons and in addition 133 spares a 2.4-meter segmented mirror for ELT’s adaptive optical system, a 4-meter concave substrate, and a 4.25-meter secondary mirror substrate, which, when completed, will be the largest convex mirror ever produced.
The characteristics of ZERODUR® have been extensively published in numerous scholarly conference papers. A list of key ZERODUR® papers, documenting designing with the material, may be found on the SCHOTT website.
At SPIE Optics and Photonics in San Diego (6-10 August 2017), several more papers will be presented on the most recent ZERODUR® results, including:
• SCHOTT optical glass in space
August 9; 10:30 am. to 10:50 am.
Authors: Ralf Jedamzik, Uwe Petzold, SCHOTT AG (Germany)
• ZERODUR 4-m blank surviving up to 20 g acceleration
August 9; 11:10 am. to 11:30 am.
Authors: Thomas Westerhoff, Thomas Werner, Thorsten Gehindy, SCHOTT AG (Germany)
• Homogeneity of the coefficient of linear thermal expansion of ZERODUR®: a review of a decade of evaluations
August 9; 11:10 AM - 11:30 AM
Authors: Ralf Jedamzik, Thomas Westerhoff, SCHOTT AG (Germany)
• Review of space radiation interaction with ZERODUR
August 9; 11:50 am. to 12:10 pm.
Authors: Antoine Carré, Thomas Westerhoff, SCHOTT AG (Germany); Tony B. Hull, The Univ. of New Mexico
• Lightweight ZERODUR: Validation of mirror performance and mirror modeling predictions
August 9; 2:20 pm. to 2:40 pm.
Authors: Tony B. Hull, The Univ. of New Mexico (United States); H. Phillip Stahl, NASA Marshall Space Flight Ctr. (United States); Thomas Westerhoff, SCHOTT AG (Germany); Martin J. Valente, Arizona Optical Systems, LLC (United States); Thomas Brooks, Ron Eng, NASA Marshall Space Flight Ctr. (United States); Ralf Jedamzik, SCHOTT AG (Germany)
• ZERODUR expanding capabilities and capacity for future spaceborne and ground-based telescopes
August 9; 3 pm. to 3:20 p.m
Authors: Thomas Westerhoff, Thomas Werner, SCHOTT AG (Germany)
SCHOTT experts will also present the following:
• Parametric criteria for optimal selection of materials for spaceborne mirrors
August 9; 10:50 am. to 11:10 am.
Authors: Tony B. Hull, The Univ. of New Mexico (United States); Stephanie Behar-Lafenetre, Thales Alenia Space (France); Dominic Doyle, European Space Research and Technology Ctr. (Netherlands); Ralf Jedamzik, Thomas Westerhoff, SCHOTT AG (Germany)
• A dense grid of narrow bandpass steep edge filters for the JST/T250 telescope: summary of results
August 10; 2:30 pm. to 2:50 pm.
Authors: Ulf Brauneck, SCHOTT Suisse SA (Switzerland); Ruediger Sprengard, SCHOTT AG (Germany); Sébastien Bourquin, SCHOTT Suisse SA (Switzerland); Antonio Marín-Franch, Ctr. de Estudios de Física del Cosmos de Aragón (Spain)
About SCHOTT
SCHOTT (us.schott.com) is a leading international technology group in the areas of specialty glass and glass-ceramics. The company has more than 130 years of outstanding development, materials and technology expertise and offers a broad portfolio of high-quality products and intelligent solutions. SCHOTT is an innovative enabler for many industries, including the home appliance, pharma, electronics, optics, life sciences, automotive and aviation industries. SCHOTT strives to play an important part of everyone’s life and is committed to innovation and sustainable success. The group maintains a global presence with production sites and sales offices in 34 countries. With its workforce of approximately 15,000 employees, sales of $2.21 billion were generated in fiscal year 2015/2016.
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