Rotating wheel scanner

Claim 1

IN A LIGHT TRACKING APPARATUS HAVING MEANS FOR FOCUSING AN IMAGE OF A LIGHT SOURCE TO BE TRACKED, AND LIGHT-RESPONSIVE MEANS FOR INITIATING ERROR SIGNALS; SCANNING MEANS LOCATED AT THE FOCAL PLANE OF SAID FOCUSING MEANS AND COMPRISING AN OPAQUE DISK ROTATABLE ABOUT THE OPTICAL AXIS OF SAID FOCUSING MEANS, A FIRST NARROW, ARCUATE LIGHT-TRANSMITTING WINDOW IN SAID DISK INTERSECTING SAID AXIS, A SECOND ARCUATE LIGHT-TRANSMITTING WINDOW IN SAID DISK CLOSELY ADJACENT, SUBSTANTIALLY PARALLEL TO, AND SHORTER THAN SAID FIRST WINDOW, THE INNER END OF SAID SECOND WINDOW BEING LOCATED SUBSTANTIALLY OUTWARDLY FROM SAID AXIS AND ON THE SAME SIDE THEREOF AS ITS OUTER END, A SCANNER WHEEL ROTATABLY MOUNTED ON SAID DISK AT A POINT WHICH IS SUBSTANTIALLY THE CENTER OF ARC OF SAID FIRST WINDOW, A FIRST CIRCULAR ROW OF HOLES IN SAID WHEEL EQUALLY SPACED FROM EACH OTHER BY THE LENGTH OF SAID FIRST WINDOW AND AT A RADIAL DISTANCE FROM SAID WHEEL CENTER EQUAL TO THE DISTANCE OF SAID CENTER FROM SAID AXIS, A SECOND CIRCULAR ROW OF HOLES IN SAID WHEEL EQUALLY SPACED FROM EACH OTHER BY THE LENGTH OF SAID SECOND WINDOW AND AT A RADIAL DISTANCE FROM SAID CENTER EQUAL TO THE RADIUS OF CURVATURE OF SAID SECOND WINDOW, MEANS FOR SIMULTANEOUSLY ROTATING SAID WHEEL ABOUT SAID CENTER AND SAID DISK ABOUT SAID AXIS AT A FIXED SPEED RATIO SUCH THAT SAID ROWS OF HOLES SWEEP RESPECTIVELY ALONG THE LENGTHS OF SAID WINDOWS, AND MEANS FOR DIRECTING LIGHT FROM SAID SCANNING MEANS TO SAID LIGHT-RESPONSIVE MEANS.