# US 2008/0186484 A1 · Optical sight having an unpowered reticle illumination source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0186484 A1 - Document ID: US20080186484A1 - Status: Published application - Kind: A1 - Application number: 11/702,685 - Filed: 2007-02-05 - Published: 2008-08-07 - Earliest claimed: 2007-02-05 - Assignees: Raytheon Company - Inventors: Kevin B. Wagner; Brien Douglas Ross - Web page: https://patentgrep.com/patent/US20080186484A1 ## CPC - G02B 23/14: Viewfinders (for photographic apparatus G03B13/02) - F41G 1/345: {for illuminating the sights} - G02B 27/34: illuminated - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - F41G: WEAPON SIGHTS; AIMING (optical aspects thereof G02B) ## Abstract An optical sight includes an optical train having an optical path therethrough, an entrance, and an exit. A reticle is visible through the exit of the optical path. An unpowered reticle illumination source has a first light source that illuminates the reticle responsive to the level of ambient light, and a second light source that illuminates the reticle with an unpowered light source. The reticle illumination source preferably has a light filter positioned so that ambient light entering the ambient-light receiver is incident upon the light filter, whereupon the light filter transmits filtered light, a light-gathering prism that receives the filtered light and has a diffusing surface disposed to illuminate the reticle using the filtered light, and an unpowered light source positioned to emit light through the diffusing surface to be incident upon the reticle. The unpowered light source may be a tritium light source. ## Claims ### Claim 1 An optical sight comprising an optical train having an optical path therethrough, an entrance, and an exit; a reticle visible through the exit of the optical path; and an unpowered reticle illumination source having a first light source that illuminates the reticle responsive to a level of ambient light, wherein the first light source comprises a light filter, and a second light source that illuminates the reticle with an unpowered light source. ### Claim 2 (depends on 1) The optical sight of claim 1, wherein the first light source comprises a light-gathering prism. ### Claim 3 (depends on 1) The optical sight of claim 1, wherein the first light source comprises an ambient-light receiver, the light filter positioned so that ambient light entering the ambient-light receiver is incident upon the light filter, whereupon the light filter transmits filtered light, and a light-gathering prism that receives the filtered light and has a diffusing surface disposed to illuminate the reticle using the filtered light. ### Claim 4 (depends on 1) The optical sight of claim 1, wherein the second light source comprises a tritium light source. ### Claim 5 (depends on 1) The optical sight of claim 1, wherein the reticle illumination source comprises an ambient-light receiver, the light filter positioned so that ambient light entering the ambient-light receiver is incident upon the light filter, whereupon the light filter transmits filtered light, a light-gathering prism that receives the filtered light and has a diffusing surface disposed to illuminate the reticle using the filtered light, and an unpowered light source positioned to emit light through the diffusing surface to be incident upon the reticle. ### Claim 6 (depends on 1) The optical sight of claim 1, wherein the optical train comprises an optically powered objective, and an optically powered eyepiece. ### Claim 7 (depends on 1) The optical sight of claim 1, wherein the optical train comprises an optically powered objective having at least one objective lens, and an optically powered eyepiece having at least one eyepiece lens. ### Claim 8 (depends on 1) The optical sight of claim 1, wherein the optical train comprises an optically powered objective having at least one objective lens, and an optically powered eyepiece having at least one eyepiece lens, and wherein the reticle is formed on the eyepiece lens. ### Claim 9 (depends on 1) The optical sight of claim 1, wherein the optical train comprises an image erector having a reflective surface thereon, and wherein the reticle is formed on the reflective surface of the image erector. ### Claim 10 An optical sight comprising an optical train having an optical path therethrough; a reticle coincident with the optical path; and an unpowered reticle illumination source comprising an ambient-light receiver, a light filter positioned so that ambient light entering the ambient-light receiver is incident upon the light filter and the light filter transmits filtered light, a light-gathering prism that receives the filtered light and has a diffusing surface disposed to illuminate the reticle using reflected filtered light, and an unpowered light source positioned to emit light through the diffusing surface to be incident upon the reticle. ### Claim 11 (depends on 10) The optical sight of claim 10, wherein the second light source comprises a tritium light source. ### Claim 12 (depends on 10) The optical sight of claim 10, wherein the optical train comprises an optically powered objective, and an optically powered eyepiece. ### Claim 13 (depends on 10) The optical sight of claim 10, wherein the optical train comprises an optically powered objective having at least one objective lens, and an optically powered eyepiece having at least one eyepiece lens. ### Claim 14 An optical sight comprising an optical train having an optical path therethrough, wherein the optical train comprises an optically powered objective having at least one objective lens, and an optically powered eyepiece having at least one eyepiece lens; a reticle coincident with the optical path; and an unpowered reticle illumination source comprising an ambient-light receiver, a light filter positioned so that ambient light entering the ambient-light receiver is incident upon the light filter and the light filter transmits filtered light, a light-gathering prism that receives the filtered light and has a diffusing surface disposed to illuminate the reticle using filtered light, and an unpowered tritium light source positioned to emit light through the diffusing surface to be incident upon the reticle.