Abstract: An additional phosphor-excitation mechanism improves the light output of a visible-light emitting phosphor. One excitation mechanism indirectly excites the visible-light emitting phosphor by first striking a non-visible-light emitting particle (such as an ultra-violet-emitting phosphor) with an electron beam, which then emits non-visible radiation that strikes a visible-light emitting phosphor. The non-visible-light emitting particles can be disposed behind and/or adjacent to die visible-light emitting phosphors. A second mechanism directly excites the visible-light emitting phosphor by directly striking the visible-light emitting phosphor with an electron beam. Thus, the same visible-light emitting phosphor is activated by the first indirect mechanism as well as the second direct mechanism.