Continuous testing at room temperature of large optics made of Zerodur has revealed a delayed elastic effect under low stress levels during both load and recovery after removal. Using a high-performance mechanical profilometer, a delayed strain of the order of 1% is realized over a period of a few weeks. The time-dependent phenomenon is elastic and reversible, but must be accounted for in various applications of optical design.
© 1992 Optical Society of America
John W. Pepi, "Delayed elastic effects in Zerodur at room temperature," Appl. Opt. 31, 115-119 (1992)