Length stability of Zerodur

O. Lindig, W. Pannhorst Thermal expansion and length stability of Zerodur in dependence on temperature and time , Appl. Opt. 24, 3330-3334 (1985)... 

O. Lindig, W. Pannhorst Thermal expansion and length stability of Zerodur in dependence on temperature and time , Appl. Opt. 24, 3330 3334 (1985) W. Pannhorst, R. Haug, E. Rodek, K. Stetter Hysteresis effects in low expansion glass-ceramics , J. Non-Cryst. Solids 131—133, 488-491 (1991)... 

Interferometric measurements lead to even higher degrees of accuracy on the other hand, these measurements are distinguished by very expensive sample preparation procedures and very long measuring times. Interferometrical measurements were performed with Zerodur , investigating its length stability by the above-mentioned standardization institutes [4.44,45,49,50]. 

Scales and gauges from the glass ceramic Zerodur are also in widespread use, since they are the temperature-independent standard for length measurement (see Fig. 4.73). This usage takes advantage of another property of Zerodur - the length stability over time. 

As the requirements for the stability of high-precision instruments in which Zerodur has to be used because of its benefits are increasing progressively, it has become apparent that there is a limit to dimensional stability if the relative length changes Al/l of a Zerodur part are required to remain of the order of 10 or less, certain temperature cycles such as... 

To study the long-term stability, Zerodur bars with a length of 400 mm were observed at a constant temperature of 20 °C at the PTB in Braunschweig from September 1973 (production of the material in 1971, last annealing in May, 1973) until 1983 [4.50]. 

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