1. An optic, comprising:an input face;
a lower exterior surface defined by a parabolic segment rotated about an axis of symmetry, the parabolic segment comprising a part of a parabola with an optical axis tilted away from the axis of symmetry when travelling upward along the optical axis, wherein a bottom end of the lower exterior surface joins a perimeter of the input face;
an upper exterior surface above the lower exterior surface, the upper exterior surface being defined by a line rotated about the axis of symmetry, the line being tilted away from the axis of symmetry when travelling upward along the line; an intermediate surface comprising an annulus, the annulus having an outer circumference that joins an upper end of the lower exterior surface and an inner circumference that joins a lower end of the upper exterior surface; and
an interior conical surface surrounded by the lower and the upper exterior surfaces, the interior conical surface being defined by a smooth curve rotated about the axis of symmetry, at least a majority of the smooth curve turning away from the axis of symmetry when travelling upward along the smooth curve, wherein:
the interior conical surface has a vertex located at the axis of symmetry and within the lower exterior surface; and
top ends of the interior conical surface and the upper exterior surface join to define an output aperture.