Cathodoluminescence (CL) - is the emission of light as a result of the interaction of a material with the electron beam. CL spectrometer and detector in SEM can be used to characterize the composition, optical and electronic properties of materials. A CL spectrometer and detector (Gatan MonoCL4 Elite) is installed on Gemini SEM. CL signal can be easily detected for direct band gap semiconductor materials, but it’s not limited only to that group of materials. It is widely used in geological and archeological sciences due to the strong emission of calcite and Quartz defects bands. In life science, CL can be used for locating and characterizing light emitting objects that do not contain heavy atoms, such as fluorophores or molecular crystals. These objects can not be detected using the back-scattered electrons (BSE) detector or EDS as usually they are mostly composed of light elements such as carbon, oxygen and nitrogen.