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A lens design method based on prescribed candela distribution is presented. By using this method, an LED lens of arbitrary beam angle can be obtained with uniformity greater than 0.8 and optical efficiency above 90%.

This paper presents a free-form lens design for indoor illumination. The lens consists of a TIR (total internal reflection) surface on the sidewall, a refractive surface on the front side, and a concave surface on the rear side. The TIR surface is decorated with a free-form profile that light rays emitted from the LED with a larger spread angle to the axis will experience a total internal refection and output from the front refractive surface. While the central part of the front refractive surface has a convex surface that makes light rays closing to the optical axis more evenly distributed. The purpose of the rear concave surface is to let light rays emitted from the LED enter the lens straightforwardly. With this lens light rays from a Lambertian-type LED light source can be redistributed so that a uniform illumination can be achieved. The optical simulation results show that the measured optical efficiency is 75% while the uniformity is 80% on a target plane of 6-m diameter and at 2.5-m away.

A simple approach is presented to design an LED lighting module to provide a uniform illumination. The reflector of the module is designed using a prescribed candle-power distribution to achieve a uniform illumination on a target surface. Both the design methodology and the construction of the reflector are stated in detail. The optical efficiency and uniformity of the module are calculated according to a ray-tracing result. In addition, the effects of the reflector's aperture and the LED chip size on the optical efficiency and uniformity are also investigated that the result can provide a reference to LED-luminaire designers and manufacturers.

A novel design of direct LED backlight is presented. The module is composed of white light LEDs, parabolic reflectors and novel lens caps. The predicted uniformity is up to 92%.

A novel vehicle headlamp structure is presented. It delivers light rays from plural LEDs via a fiber to the headlamp to form a legal low-beam pattern with a predicted optical efficiency of 45%.

A freeform lens design method based on energy mapping and complementary optimization approaches is proposed to achieve uniform illumination with extended light-emitting diode (LED) sources. This method is primarily derived from a simple source–a target energy mapping approach, while a complementary illuminance on the target plane is introduced to optimize the primary axisymmetric lens so that the profile of the lens can be reformed to produce uniform illumination when applying an extended LED source. By using this optimization method, the illuminance uniformity and optical efficiency of the lens can be improved, respectively, from 0.56 to 0.85 and from 92.4% to 94.3% for an LED light source with chip diameter of 8.9 mm, while the aspect ratio of the lens clear aperture to the source diameter is only 3.8.

We present a freeform lens for application to LED uniform illumination. This lens, which is designed with a method of simple source-target luminous intensity mapping, can produce irradiance uniformity of greater than 0.8 and optical efficiency above 90% with an arbitrary half-beam angle greater than 45 deg. Typically, as compared with a conventional source-target energy mapping method, this design method can achieve better optical performance of lenses for general LED lighting. When a non-Lambertian-type light source is employed, for example, the chip on board LED, the use of the method can result in a compact LED lens without losing the optical performances of high irradiance uniformity and high optical efficiency as yielded by lenses for Lambertian-type LED light sources.

We present a simple freeform lens design method for an application to LED collimating illumination. The method is derived from a basic geometric-optics analysis and construction approach. By using this method, a highly collimating lens with LED chip size of 1.0 mm × 1.0 mm and optical simulation efficiency of 86.5% under a view angle of ± 5 deg is constructed. To verify the practical performance of the lens, a prototype of the collimator lens is also made, and an optical efficiency of 90.3% with a beam angle of 4.75 deg is measured.

A fiber-and-LED-based vehicle headlamp is presented in which light rays emitted from multiple high-power LEDs are gathered using a light collector and then guided into a projector lamp via an optical fiber. This proposed headlamp is intended to reduce the lamp size and the heat-dissipation problem simultaneously. Detailed geometric analysis of the headlamp is given, and the optical efficiency for each component part is also calculated using a TracePro program. The computer simulation results show that the headlamp can produce a legal Economic Commission for Europe low-beam pattern with a total optical efficiency up to 49.4%, and only eight 5-W LEDs (120 lm each) are required.