Jin-Jia Chen

Freeform lens design for LED collimating illumination

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.

Freeform surface design for a light-emitting diode–based collimating lens

A freeform collimating lens is designed to project light rays emitted from an LED light source to a far target plane. Generally, the projection distance is assumed to be more than 100 m, and the light beam to have negligible divergence. The lens consists of a total internal reflection (TIR) side surface, a spherical surface in the rear, a vertical plane surface in the outer part of the front, and a freeform refractive surface in the central part of the front. Light rays emitted from the LED source with large spread angles hit the TIR surface and are redirected parallel to the light axis, and those having small spread angles will be collimated by the freeform refractive surface, which is designed with a simple approximation method, and then travel parallel to the light axis. Computer simulation results show that an optical efficiency of 81.5% is achieved under a view angle of ±5 deg and for a 1 mm×1 mm LED source.

Computer modeling of a fiber-and-light-emitting-diode-based vehicle headlamp

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.

Free-form lens design for LED indoor illumination

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.

LED lighting module design based on a prescribed candle-power distribution for uniform illumination

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 reflectors 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.

Light-emitting diode cover lens design for large-scale liquid crystal device television backlight

We present a high-performance cover lens for light-emitting diode (LED) light sources to be applied to large-scale liquid crystal device television (LCD-TV) backlight modules. The cover lens with simple structure can redistribute light rays emitted from an LED light source to make the light distribution more extended so that the luminance uniformity of the backlight module can be increased. To gain a better performance, the parameters of the lens structure are optimized using a genetic algorithm. The simulation result shows that using the cover lens can achieve a luminance uniformity of 94.75% and an optical efficiency of 72.29% for a 46-in LCD-TV backlight module.

Complementary optimization method of freeform lens design for uniform illumination with extended light-emitting diode sources

Abstract. 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.

A Design of LED Panel Lamp for Indoor Illumination

An LED panel lamp is presented for general indoor illumination. This lamp consists of arrayed LED light sources with each LED united with an evening lens so that the Lambertian distribution of LED light is altered, and the illuminance on a target plane can be uniform. The computer simulation result shows that the illuminance uniformity is 0.737, and the maximum illuminance is 140 lx on a detecting screen at 1.5 m away.

Highly efficient Y-junctions with arc-bend branch structures of sunlight guiding systems for indoor illumination

ABSTRACT This paper proposes both symmetrical and asymmetric Y-junctions with arc-bend branch structures for auxiliary indoor-illumination applications. These arc-bend branch structures can be used as a concave-mirror-like light guide, to change the direction of beam propagation and also to converge the beam spread angle. Optical simulation results show that the proposed arc-bend Y-junctions can achieve an inner coupling efficiency, not including plastic/air interfaces, above 90% in both usages: beam combiner and splitter. Particularly, when the applied branch opening angle becomes large, this high optical efficiency becomes more significant than those of linear straight Y-junctions. Moreover, it is also confirmed that the coupling efficiency of the symmetric arc-bend junction can be as high as 90.0%, and the asymmetric coupling efficiency is 93.4%, even if the branch opening angle is quite large.

Design of Relay Lens Based on Zero Seidel Aberrations

Seidel aberration has been used successfully in finding starting points for a lens system, especially in designing a relay lens, which may have the symmetric condition with aperture stop, and the benefit of zero Seidel aberrations of com, distortion, and transverse chromatic aberration. In this paper, a relay lens has been designed based on the principle of zero Seidel aberrations. The MTF of the design is near diffraction limited, which has an excellent image performance of high resolution.