TABLE OF CONTENTS When in 1957 Corning Glass Works announced the invention of a new class of materials called glass ceramics, Schott started research in this field to acquire competence for future product developments. Schott mainly concentrated its research on glass ceramics in the Li 2O-Al 2O 3-SiO 2-composition field and contributed to a broadened understanding of the nucleation and crystallization phenomena; for example, Sack and Scheidler [4.1] were the first to propose the use of a combination of the nucleating agents TiO 2 and ZrO 2. In these early stages of research and development, product ideas mainly centered around cookware. In discussions during international meetings with scientists from other laboratories, Schott scientists learned that the low-expansion Li 2O-Al 2O 3-SiO 2 (LAS) glass ceramics were considered as substrate materials for telescope mirror blanks, and perhaps they dreamed of developing such a material. But Schott was well aware that the development of a telescope mirror substrate material and its realization in the form of large castings depended not only on the corresponding demand but equally on the willingness of an institution to supply sufficient funding.
The situation changed suddenly when Dr. Els sser from the Max Planck Institute (MPI) of Astronomy in Heidelberg approached Schott in 1966 asking whether Schott thought that large castings with about 4 m in diameter could really be fabricated from the new low-expansion...
