Abstract: A portable, battery powered, cross-hair illuminator for rifle scopes and similar instruments. In this embodiment, the Reticle Illuminator is a bolt-on attachment to rifle scopes or similar sighting devices using cross-hairs or other aim point configurations. The Reticle Illuminator is attached to the occular end of a rifle scope by means of an expandable clamp band. The evice itself consists of a main housing to which the clamp band screw is attached. Within the main housing is the electrical circuitry, including battery sleeve, battery switch, and lamp. When activated by switch, the system emit a beam of light into an optical fiber, surrounded by a transmitting tube, making possible the precise projection of light through a conventional lense system to strike and illuminate an unaltered reticle.