Multi-channel freeform optics for glare-free lighting

Glare and visual discomfort are important factors that should be taken into account in illumination design. Conventional freeform optics offer perfect control over the outgoing intensity distribution, but few control over the near-field luminance distribution. Observing the emitted light from a high-brightness LED through a freeform lens, yields a high peak luminance that can result in glare. Diffusors can be used to reduce these peak luminances, but such components do not offer accurate control over the resulting intensity pattern. An alternative approach to reduce the observed peak luminance is by spreading the emitted light over multiple optical channels via freeform lens arrays. Such freeform arrays still allow excellent control over the resulting intensity distribution. In this paper the design of freeform lens arrays is discussed in both 2D and 3D. The possibilities and main limitations of the resulting components are discussed in detail by considering a few examples. In order to understand the design algorithms for multi-channel freeform optics, the paper starts with a brief introduction to the design of single-channel freeform optics for obtaining prescribed illumination patterns.