Abstract: A process for forming glass or glass ceramics is disclosed, wherein a glass ceramics form (12) is made from a starting glass by molding, which is transformed by a heat treatment into a keatite glass ceramic comprising predominantly keatite mixed crystals. With such a keatite glass ceramics form (12) formed bodies can be prepared from blank parts by sagging under gravity force at a temperature above the glass transition temperature of the blank part (14).

Abstract: A lithium-aluminosilicate glass ceramic is transformed by a suitable heat treatment into a glass ceramic comprising at least 80 vol.-% of keatite mixed crystals. This may be utilized for the preparation of optical or mechanical high-precision parts having a high temperature resistance, a good stability and compatibility with components consisting of metals having a small coefficient of thermal expansion based on nickel and iron, such as Invar®.

Abstract: The invention relates to a one-dimensional calibration standard for coordinate measuring devices, especially for optical coordinate measuring devices, so-called laser trackers that are provided with a rod-shaped calibration device. The inventive device is characterized in that the rod-shaped calibration device consists of a single material having a thermal expansion coefficient of <5×10−6K−1 and that the rod-shaped calibration device is provided with at least two bores at predetermined calibrated intervals into which the reflective devices of the optical measuring device or the balls used for the calibration of scanning coordinate measuring systems can be exactly and reproducibly inserted and withdrawn in order to calibrate the coordinate measuring device.