Freeform optics for illumination: past, present, and future

Freeform optics for illumination, pioneered over 20 years ago, are now widely used to light up streets, automobiles, architecture and more. But many questions remain: Do we have good, accessible design methods, especially for extended sources? Do we have proven processes to estimate and specify tolerances, to ensure full production yield without overengineering? Do we fully understand diffractive structures on freeform surfaces? The talk discusses the progress of design and manufacturing methods over the last 30 years, shows the knowledge gaps we're suffering from, and concludes with an outlook to a non-obvious but exciting new approach for coherent light: What happens when we combine freeform surfaces with scattering and spatial light modulation?