Focussed ion beam milling of silica microspheres

Focussed ion beam milling, combined with secondary ion and secondary electron imaging, has been used to evaluate the internal homogeneity of silica glass microspheres. Internal inhomogeneities that will result in non-uniform optical properties are found. The method is demonstrated as suitable for evaluating internal optical quality of the silica microspheres qualitatively. Basic studies to determine whether differences in chemical composition can be differentiated from density differences and topological contouring are required before the technique can be evaluated for more quantitative application.