The present embodiments provide methods and apparatuses for providing prescribed
illumination. Some embodiments provide lenses that include a two-dimensional beam-forming
lens-profile where the profile acts to deflect light rays from a light source into
a relatively narrow output beam. A zone of higher refractive index than that of
the area outside the profile is enclosed where the higher refractive-index zone
admits the light rays, a transverse axis of revolution is further included and
extends transversely across and outside of the lens-profile so that the transverse
axis extends generally laterally with respect to a luminous centroid-direction
of the output beam. The lens further includes a surface of revolution formed by
circularly sweeping the lens-profile about the axis of revolution forming a circumferential
beam from the output beam emitted by said surface of revolution.