A High Efficiency Cathodoluminescence System and its Application to Optical Materials

A high collection efficiency spectroscopic cathodoluminescence (CL) system based on an in-line ellipsoidal mirror has been constructed for use on a Cambridge S250 scanning electron microscope (SEM). It can be fitted to or removed from the SEM in about 30 minutes and requires no significant modification of the instrument. It can be used to obtain total CL images, monochromatic CL images or CL spectra with an ultimate spectral resolution of 1 nm. The system has been applied to the study of doped synthetic quartz crystals, optical fibres and optical fibre preforms, and to yttrium aluminium garnet, bismuth silicon oxide and potassium tantalum niobate crystals. The CL technique has proved particularly valuable in the study of quartz and his revealed a number of interesting features related to crystal growth. For optical fibres and their preforms CL provides a convenient method of monitoring the distribution of germanium, used as a dopant to increase the refractive index in the core region of the fibre