Light modulation system for photosensitive tracking device

Claim 1

A SCANNING DEVICE FOR LIGHT SOURCE TRACKING DEVICES; SAID SCANNING DEVICE COMPRISING A PLATE HAVING A SINGLE APERTURE THEREIN AND A DRIVING MEANS CONNECTED TO SAID PLATE; SAID DRIVE MEANS OSCILLATING SAID PLATE ABOUT A CENTRAL POSITION WITH SIMPLE HARMONIC MOTION AT A PREDETTERMINED FREQUENCY OF OSICILLATION; SAID TRACKING DEVICE INCLUDING MEANS FOR DIRECTING AN IMAGE OF THE LIGHT SOURCE TO BE TRACKED BY SAID SCANNING DEVICE TOWARD SAID PLATE AND A LIGHT SENSING MEANS; SAID PLATE BEING INTERPOSED BETWEEN THE LIGHT SOURCE BEING TRACKED AND SAID IMAGE DIRECTING MEANS; SAID DRIVING MEANS MOVING SAID APERTURE ALONG A LINE TO CAUSE INTERMITTENT REGISTRY WITH SAID IMAGE OF SAID LIGHT SOURCE TO PERMIT INTERMITTENT IMPINGEMENT OF LIGHT ON SAID LIGHT SENSING MEANS; SAID LIGHT SENSING MEANS GENERATING A SIGNAL HAVING A FREQUENCY EQUAL TO TWICE THE FREQUENCY OF OSCILLATION OF SAID PLATE WHEN THE CENTER OF SAID IMAGE IS AT SAID CENTRAL POSITION AND GENERATING A SIGNAL HAVING A FREQUENCY EQUAL TO THE FREQUENCY OF OSCIALLTION OF SAID PLATE AS AT LEAST A PORTION THEREOF WHEN SAID IMAGE IS DISPLACED FROM SAID CENTRAL POSITION.