Concave Wide Emitting Lens for LED Useful for Backlighting

Lenses for LEDs are described that efficiently create a substantially uniform light emission across a surface of a backlight box. The backlight may illuminate an LCD. A wide-emitting lens refracts light emitted by an LED die to cause a peak intensity to occur within 35-65 degrees off the die's center axis, normal to the die's top surface, and an intensity along the center axis to be between 40% and 90% of the peak intensity. The lens is concave over the die and has smooth edges that transition into the lens sidewalls. The direct emissions of the lenses from a plurality of LEDs arranged on a base surface in a backlight box combine together to uniformly illuminate a light output surface of the backlight box.