Planar waveguide LED illuminator with controlled directionality and divergence.

We present a versatile illumination system where white light emitting diodes are coupled through a planar waveguide to periodically patterned extraction features at the focal plane of a two dimensional lenslet array. Adjusting the position of the lenslet array allows control over both the directionality and divergence of the emitted beam. We describe an analytic design process, and show optimal designs can achieve high luminous emittance (1.3x10⁴ lux) over a 2x2 foot aperture with over 75% optical efficiency while simultaneously allowing beam steering over ± 60° and divergence control from ± 5° to fully hemispherical output. Finally, we present experimental results of a prototype system which validate the design model.