Patent ID: 8449150

Claim:
A device comprising: a light-emitting diode module with a Lambertian light output; a lens made of a transparent material and having symmetry about a longitudinal axis, the lens comprising: an interior surface proximate the light-emitting diode module and having a concave portion centered on the longitudinal axis, such that any light entering the lens from the light emitted from the light-emitting diode module enters through the concave portion, the interior surface further having a total internal reflection portion circumferentially surrounding the concave portion, such that any light ray that enters the lens through the concave portion and directly strikes the total internal reflection portion does so at an incident angle greater than a critical angle for the lens; and an exterior surface facing away from the light-emitting diode module and through which light exits the lens, the exterior surface having a lateral edge and a distal curvilinear portion further including a distal convex portion and a distal concave portion, the distal convex portion defining a maximum distal longitudinal extent of the lens; wherein the interior and exterior surfaces define a batwing-shaped structure; the lens converting light rays emitted from the light-emitting diode module into a generally uniform output distribution of light rays emerging from the lens; wherein the lens includes an inner longitudinal thickness proximate the longitudinal axis, an outer longitudinal thickness proximate the lateral edge of the exterior surface, and an intermediate longitudinal thickness between the longitudinal axis and the lateral edge and thus between the inner Longitudinal thickness and the outer Longitudinal thickness, the intermediate longitudinal thickness being greater than both the inner longitudinal thickness and the outer longitudinal thickness.