Status Of The Production Of 8M Zerodur Mirror Blanks

In 1988, Schott Glaswerke in Mainz received an order from the European Sourther Observatory to produce four 8m Zerodur mirror blanks in the form of thin menisci for their very large telescope. In this paper the experience gained when performing different process steps is presented and discussed. This includes a comparison of theoretical calculations during the planning phase with actual experimental results.