Window to distant galaxies

Published: 1-Aug-2017

SCHOTT wins major contract to produce mirror substrates for the world’s largest telescope

SCHOTT is set to deliver a total of 949 mirror substrates made of ZERODUR to the European Southern Observatory (ESO). Thanks to the headquarters’ investment of more than €10 million, the company is well prepared to respond to the increased demand.

Chile’s Atacama Desert is home to the ESO‘s Extremely Large Telescope — or ELT — the world’s largest telescope. By 2024, the telescope is planned to discover unexplored galaxies and exoplanets, to deliver unprecedented image quality of them.

The gigantic primary mirror, known simply as “Mirror 1” or “M1”, has the main function of collecting light from the cosmos and transferring it further via additional mirrors onto the observatory’s scientific instruments.

The international technology group SCHOTT has just been awarded the contract to provide the substrate components — 798 hexagons made of ZERODUR glass-ceramic for the assembly of the enormous primary mirror.

SCHOTT earlier provided substrates for other ELT mirrors

After the first ZERODUR components for the segmented fourth mirror (M4) left SCHOTT’s Mainz production facility in 2016, the next order followed at the beginning of 2017 for the substrates to be used in the secondary (M2) and tertiary mirrors (M3). Thus, the first four ELT substrates will soon be equipped with ZERODUR.

Dr Frank Heinricht, Chairman of the Board at SCHOTT, said: “We are very proud to play a significant role in the ELT project. We are also extremely pleased that because of our know-how, distant galaxies can finally be viewed with unprecedented sharpness.

"The ESO order for the production of substrates for the ELT primary mirror represents the single-largest contract in terms of astronomical projects, which SCHOTT has ever been awarded. At our ZERODUR competency center in Mainz, we have invested more than €10m over the last several years to secure and expand our excellent market position for the future.”

Christoph Fark, Executive Vice President of Advanced Optics at SCHOTT, said: “Providing more than 900 ZERODUR panels for the hexagons with the start of series production in 2020 will place a high workload on the manufacturing facility at our Mainz headquarters.

"However, with the addition of a second ZERODUR melting tank, which was recently commissioned, we are certain that we will be able to effortlessly meet the continuing high demand for the material. In addition, we have added more cutting-edge CNC machines at our facility, which contribute to fulfilling the growing customer requirements.”

Substrates made in Germany

The casting and grinding of the 949 ELT substrate elements takes place at SCHOTT headquarters in Mainz, Germany, while the polishing and coating of them is handled by the French company Safran-Reosc, which has many years of experience in working with ZERODUR. The substrates for the primary mirror are scheduled to be gradually delivered through to March 2024.

When it comes to the production of materials for astronomical applications, SCHOTT has accumulated decades of experience. Since 1903 the company, which is part of the Carl Zeiss Foundation, has been providing substrates in various dimensions for use in both space telescopes and terrestrial ones.

In 2018, ZERODUR will celebrate the 50th anniversary of its development. The de facto standard for substrates has proven its reliability in numerous mega telescopes around the world, including the Very Large Telescope (VLT), which is positioned not far from the ELT and has a primary mirror containing four ZERODUR segments, with an overall diameter of 8.2 m. The VLT is also known as having the world’s largest substrate cast as single unit.

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