Patent ID: 8534901

Claim:
A collimating waveguide, comprising: an input surface comprising a microstructure to receive radiant electromagnetic energy from a point source, wherein the microstructure comprises a plurality of linear prisms each one defining an apex angle, a convex portion defining a radius, and a concave portion defining a radius, wherein the radius of the convex portion is greater than the radius of the concave portion; an output surface to emit an output beam of substantially collimated radiant electromagnetic energy; a first collimating surface to receive a beam of the radiant electromagnetic energy entering from the input surface traveling in a first direction and to reflect the radiant electromagnetic energy into a substantially collimated beam of radiant electromagnetic energy traveling in a second direction, which is the reverse of the first direction, wherein the first collimating surface comprises a curved surface, wherein the curved surface is defined by a first radius of curvature R 1 about a first axis and a second radius of curvature R 2 about a second axis, wherein the first and second axes are orthogonal; and a second collimating surface to receive the substantially collimated beam of radiant electromagnetic energy and to redirect the substantially collimated beam toward the output surface.