A cathodoluminescence (CL) microscope combines methods from electron and regular (light optical) microscopes. It is designed to study the luminescence characteristics of polished thin surfaces irritated by an electron beam. To prevent charging of the sample, the surface must be coated with a conductive layer of gold or carbon.

Someone using CL-microscopy can view structures within crystals or fabrics which cannot be seen in normal light conditions. Thus, for example, valuable information on the growth of minerals can be obtained. CL-microscopy is used in geology, mineralogy and material sciences (ceramics, glass, concrete etc.).

CL color and intensity are dependent on the characteristics of the sample and on the working conditions of the microscope. Here, acceleration voltage and beam current of the electron beam are of major importance.