A sighting device for day and night use having a beam-splitting means mounted in the line of sight between a target and the user's eye, a first source of light, being a self-energized source of artificial light, a second source of light, being an ambient-light admitting element, at least one aiming mark...http://www.google.com.au/patents/US4764011?utm_source=gb-gplus-sharePatent US4764011 - Sighting device for day and night use
