Image Number 4 for United States Patent #4243187.
A line of sight guidance system in which the radiated output of a pulsed laser is spatially modulated to produce a beam radiated from an optical projector along a first axis, including a missile or projectile carrying a beam receiver and signal decoder which receives and decodes information in the beam to enable the missile to seek beam center, is provided with apparatus for generating a lead angle axis reference for the missile. The basic technique comprises FM modulating the rotational rate of an orbitally driven projected beam chopping spoked reticle. The FM modulation amplitude is chosen to equal the magnitude of the desired angular change of the projected spatially coded axis, while the FM modulation phase is made to equal the direction in which the projected spatially coded axis is shifted. The receiver at the missile interprets the image of the recticle pattern as if the receiver where displaced from the unmodualted first axis position in a direction from beam center as indicated by the modulation phase. Since the missile is controlled to the beam axis center, it follows the coded axis shift.