Methods and apparatus for a guidance system according to various aspects
of the present invention comprise include an energy concentrator
configured to transmit an energy entering the entrance through the exit
if the energy enters the entrance within a predetermined acceptance
angle, and reject the energy entering the entrance if the energy enters
the entrance outside the predetermined acceptance angle. The system may
further comprise a detector coupled to the exit of the energy
concentrator and configured to generate signals corresponding to a
location of the transmitted energy incident upon the detector.