A method for evaluating the thermal dimensional stability and homogeneity of beryllium mirrors is described. Thermal dimensional instabilities are shown to be highly dependent on crystalline anisotropy. An x-ray quality control technique is discussed which can be used to predict optical performance under changes in ambient temperature.
W. R. Goggin and J. W. Moberly, "Thermal Dimensional Instabilities of Beryllium Mirrors," Appl. Opt. 9, 2691-2696 (1970)