title: Ultra-compact LED lens with double freeform surfaces for uniform illumination.
abstract: An ultra-compact rotational symmetric lens with double freeform surfaces based on the edge-ray principle is designed in this paper. The lens redistributes light emitting from a Lambertian LED light source to achieve uniform illumination within the target area. The initial design is optimized for optics compactness under structural constraints and illumination requirement using the genetic algorithm. A design for the double-freeform-surface lens with a height of the optics system h = 12.56 mm for a circular LED source with a diameter D = 10 mm is demonstrated for uniform illumination within 45° and thus achieves optics compactness h/D = 1.256, which is half of that achieved by the single-freeform-surface lens. The Monte-Carlo ray-tracing result shows an illumination circular area with a clear cut-off at R = 1000 mm at the target plane in a distance H = 1000 mm. The uniformity within the target illumination area is greater than 0.9 and the light output efficiency is as high as 0.9865.
authors.forename: Shixiong
authors.initials: S
authors.lastname: Hu
authors.forename: Kang
authors.initials: K
authors.lastname: Du
authors.forename: Ting
authors.initials: T
authors.lastname: Mei
authors.forename: Lei
authors.initials: L
authors.lastname: Wan
authors.forename: Ning
authors.initials: N
authors.lastname: Zhu