👉 Cathodoluminescence is a phenomenon in which light emitted from a material changes color due to its presence. This change in color occurs because of the emission of electrons from the material, which are then re-emitted into space by collisions with other atoms or molecules. In a cathode ray tube (CRT) display, light is converted into an electric current that is directed towards a cathode, where it emits electrons and returns to the cathode. These electrons collide with atoms in the crystal