Attachment for a sighting device for sighting in opposite directions perpendicular to the optical axis of the device

Claim 1

A LINEAR COLLINATING ATTACHMENT APPARATUS FOR A TELESCOPE SIGHTING DEVICE FOR ACCURATELY DETERMINING THE LINE OF SIGHT BETWEEN TWO FIXED POINTS, SAID APPARATUS COMPRISING, A LENS HOLDING TUBE FOR ATTACHMENT TO THE OBJECTIVE END OF SAID SIGHTING DEVICE TO EXTEND PERPENDICULAR TO THE OPTICAL AXIS THEREOF LINEARLY IN OPPOSITE DIRECTIONS, FOCUSSING LENSES MOUNTED AT EACH END OF SAID LENS HOLDING TUBE, AN ADJUSTABLY MOUNTED MIRROR MOUNTING BAR POSITIONED PARTIALLY WITHIN SAID LENS HOLDING TUBE AND IN PERPENDICULAR RELATIONSHIP THEREWITH AND WITH SAID SIGHTING DEVICE, TWO LATERALLY ADJACENT CROSSED MIRROR SURFACES POSITIONED AT RIGHT ANGLES TO EACH OTHER ON SAID MOUNTING BAR, THE OPTICAL AXIS OF SAID SIGHTING DEVICE FORMING 45 DEGREE ANGLES WITH THE SURFACES OF SAID MIRRORS AND ARRANGED TO REFLECT A PART OF THE IMAGES RECEIVED FROM SAID FOCUSSING LENSES THROUGH THE EYEPIECE OF SAID SIGHTING DEVICE, EACH OF SAID MIRRORS REFLECTING ONE-HALF OF THE IMAGE WITHIN THE FIELD OF VIEW OF EACH CORRESPONDING FOCUSSING LENS, SAID IMAGES BEING IN JUXTAPOSITIONED RELATIONSHIP TO EACH OTHER PRODUCING A SPLIT-IMAGE PRESENTATION OF THE FIELD OF VIEW OF THE FOCUSSING LENSES, THEREBY ALLOWING AN OBSERVER TO DETERMINED THE ALIGNMENT BETWEEN TARGETS IN OPPOSITE DIRECTIONS PERPENDICULAR TO THE OPTICAL AXIS OF SAID SIGHTING DEVICE.