ZERODUR for stressed mirror polishing II: improved modeling of the material behavior

摘要

In the preceding part I of this paper stressed mirror polishing was stated as one of the processes assumed for the polishing ofnon-axisymmetric mirror blanks like those for the two ELT projects (the ESO E-ELT and the TMT). For this process it isimportant to have a precise knowledge of the elastic behavior of the glass ceramic mirror substrate materials. In realityglasses and glass ceramics do not react instantaneously to stresses at room temperature. This effect is called "delayedelasticity".It was shown that the delayed elasticity effect of ZERODURsup®/sup is small in size (less than approximately 1% of the applieddeformation) and fully reversible in time. A mathematical model on the relaxation of shear modulus and bulk modulus ofZERODURsup®/sup has been introduced to predict the delayed elasticity at room temperature and different load cases. This secondpaper is focusing on an updated model approach with the target to improve the model prediction accuracy. The modelresults will be compared to measurements of the effect on a 1.5 m E-ELT mirror blank at L-3 Communications, Tinsley.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.