Optical correlation navigation system

Claim 1

NAVIGATION APPARATUS FOR TAKING A POINT FIX FROM AN AIRBORNE VEHICLE IN FLIGHT ALONG A PREDETERMINED FLIGHT PATH AND REFERENCED TO A PREDETERMINED POINT ALONG SAID PATH INCLUDING: IMAGE MEANS FOR SIMULATING, IN REDUCED SCALE, A STRIP OF THE REAL TERRAIN EXTENDING GENERALLY TRANSVERSE TO AND INTERSECTING WITH THE FLIGHT PATH OF SAID VEHICLE, SAID STRIP OF REAL TERRAIN INCLUDING SAID PREDETERMINED POINT AT THE INTERSECTION OF SAID FLIGHT PATH AND SAID STRIP OF REAL TERRAIN, AN APERTURE FOR LIMITING THE FIELD OF VIEW OF THE TERRAIN BELOW SAID VEHICLE AND FOR LIMITING THE PORTION OF SAID IMAGE MEANS EXPOSED TO SAID FIELD, MEANS FOR CONTINUOUSLY DRIVING SAID IMAGE MEANS PAST SAID APERTURE FOR CONTINUOSLY CHANGING THAT PART OF THE IMAGE OF SAID STRIP OF TERRAIN EXPOSED IN SAID APERTURE, SAID IMAGE MEANS, APERTURE AND DRIVING MEANS COMBINING TO PROVIDE A CORRELATION SPOT WHEN THE EXPOSED PART OF SAID IMAGE MEANS IS IN REGISTRATION WITH THAT PART OF SAID STRIP OF REAL TERRAIN IN SAID FIELD OF VIEW, A FIXED RETICLE HAVING ALTERNATELY POSITIONED OPAQUE AND TRANSPARENT STRIPES FOR ALTERNATELY BLOCKING AND PASSING SAID CORRELATION SPOT, MEANS FOR CONVERTING LIGHT ENERGY INTO CORRESPONDING ELECTRIC ENERGY POSITIONED FOR RECEIVING LIGHT ENERGY PASSED THROUGH SAID RETICLE, AND MEANS FOR DETECTING ELECTRIC SIGNALS FROM SAID CONVERTING MEANS WHICH CORRESPOND TO THE LIGHT ENERGY OF THE CORRELATION SPOT PASSING THROUGH SAID RETICLE FOR DETECTING WHEN A PORTION OF SAID IMAGE MEANS AND A PORTION OF SAID STRIP OF REAL TERRAIN ARE IN REGISTRATION.