Allen Jong-Woei Whang

Designing Uniform Illumination Systems by Surface-Tailored Lens and Configurations of LED Arrays

Light-emitting diodes (LEDs) are gradually becoming the preferred choice for many lighting applications that require uniform illumination distribution. LED sources are usually composed of several individual LEDs which must be mounted on a panel as a lighting module. Therefore, the design is quite important for achieving a good uniform illumination distribution before a LED lighting module is produced. This paper presents a theory and design method by systemic concepts and focuses on the study of optical properties. We can design, efficiently, a LED lighting module and achieve a satisfactory uniformity by this theory and method, the design of a uniform LED illumination system. By this method, we not only obtain the maximally flat illumination distribution but also the emitting angle of the system can be designed at will. This method and theory will offer a preferable choice when LED lighting modules become the main stream for the lighting market in the future. Here, the light source is approximately defined as a point light source with cosine irradiance distribution.

Natural light illumination system

In recent years, green energy has undergone a lot of development and has been the subject of many applications. Many research studies have focused on illumination with sunlight as a means of saving energy and creating healthy lighting. Natural light illumination systems have collecting, transmitting, and lighting elements. Today, most daylight collectors use dynamic concentrators; these include Sun tracking systems. However, this design is too expensive to be cost effective. To create a low-cost collector that can be easily installed on a large building, we have designed a static concentrator, which is prismatic and cascadable, to collect sunlight for indoor illumination. The transmission component uses a large number of optical fibers. Because optical fibers are expensive, this means that most of the cost for the system will be related to transmission. In this paper, we also use a prismatic structure to design an optical coupler for coupling n to 1. With the n-to-1 coupler, the number of optical fibers necessary can be greatly reduced. Although this new natural light illumination system can effectively guide collected sunlight and send it to the basement or to other indoor places for healthy lighting, previously there has been no way to manage the collected sunlight when lighting was not desired. To solve this problem, we have designed an optical switch and a beam splitter to control and separate the transmitted light. When replacing traditional sources, the lighting should have similar characteristics, such as intensity distribution and geometric parameters, to those of traditional artificial sources. We have designed, simulated, and optimized an illumination lightpipe with a dot pattern to redistribute the collected sunlight from the natural light illumination system such that it equals the qualities of a traditional lighting system. We also provide an active lighting module that provides lighting from the natural light illumination system or LED auxiliary sources, depending on circumstances. The system is controlled by a light detector. We used optical simulation tools to design and simulate the efficiency of the active module. Finally, we used the natural light illumination system to provide natural illumination for a traffic tunnel. This system will provide a great number of benefits for the people who use it.

Guiding Light From LED Array Via Tapered Light Pipe for Illumination Systems Design

In illumination systems, it is often necessary to get a structure that can have good performance on uniformity. Although light-emitting diodes (LEDs) are replacing conventional light sources in illumination systems, they have nonuniformity and a large view angle. In this paper, an LED illumination system has been designed that can use color sequential to replace the color wheel for projector and also can mix color to get the color you want. An optical element tapered light pipe is also used in this structure, and we investigate the mechanism of irradiance distribution. It assists in the design of light pipe for different applications. The efficiency is above 80% and the uniformity is better than 60%. The formation of irradiance distribution in the tapered light pipe is discussed, both analytically and numerically. The result of the simulation verifies that efficiency of this structure is well enough for the illumination of both car headlights and interior lighting. This illumination system also provides a good color-mixing effect that can replace arc lamps or fluorescent lamps.

Using prismatic structure and brightness enhancement film to design cascadable unit of static solar concentrator in natural light guiding system

Due to the energy crisis, the principle of green energy gains popularity. This leads the increasing interest in renewable energy such as solar energy. How to collect sunlight for indoor illumination is our ultimate target. A Natural Light Guiding System includes collecting, transmitting, and lighting parts. To date, most studies of collecting part have delicate in dynamic concentrators which include sun tracking systems. They are powered by small electric motors and require some type of control module to follow sun path, so it requires maintenance and adds a good bit of complexity to the system. The application area of dynamic concentrator is limited. In order to create a low cost, easily set up, and applied on large area structure, we design a unit of static concentrator to collect sunlight for indoor illumination which is prismatic and cascadable. The unit is made up of prismatic structure and can collect the nature light, sunlight, for indoor illumination. For offer more saving energy and more stable illumination, we consider the total collected energy in the whole day and the relationship between the efficiency of the static concentrator and time. We change the size of prism to be different and add the BEF structure to improve the unit. According to the simulation, the prismatic structure with different right-angle prism could advance the total collected energy and the BEF could advance the stabilization of efficiency in the whole day.

Design of a high-efficiency collection structure for daylight illumination applications

In developing a high-quality natural light illumination system (NLIS), the primary considerations include how to increase system efficiency and broaden its applications. This paper describes the conception, design, and analysis of a daylight collector that presents the combined advantages of excellent efficiency and a compact size. The collector structure consists of extendable two-channel collecting units, a planar light guide, and a central coupler to improve light collection efficiency and increase surface area. In this study, two types of daylight collectors are proposed for illumination applications with different light patterns. With these collectors, the NLIS can now provide sufficiently powerful light for indoor illumination.

An innovative vehicle headlamp design based on a high-efficiency LED light pipe system

We propose an innovative vehicle headlight design based on a highly efficient LED light pipe system. In the system, light rays are emitted from multiple high-power LEDs in front of a total internal reflection (TIR) lens. After passing through the TIR lens, the rays are divided into two beams by a prism splitter, and each beam is guided to each headlamp by a light pipe. We propose the system because it uses fewer LEDs but provides enough lumens and reduces the number of TIR lenses required. Detailed analysis of the system is given, and the simulation results show that the headlamp produces a legal Economic Commission for Europe (ECE) low-beam pattern, with a total optical efficiency up to 40.2%, when four LED (Lumileds-K2) sources are used.

An active lighting module with natural light guiding system and solid state source for indoor illumination

Recently, many researches focus on healthy lighting with sunlight. A Natural Light Guiding System includes collecting, transmitting, and lighting parts. In general, the lighting module of the Natural Light Guiding System only uses scattering element, such as diffuser, to achieve uniform illumination. With the passive lighting module, the application of the Natural Light Guiding System is limited because sunlight is dynamic source. When the sunlight is weak at morning, at evening, or on cloudy day, the illumination system is fail. In this paper, we provide an active lighting module that includes the lighting part of Natural Light Guiding System, LED auxiliary sources, optical elements, and optical detector. We use optical simulation tool to design and simulate the efficiency of the active module. The optical element can redistribute the sunlight only, LED light only, or sunlight with LED light to achieve uniform illumination. With the feedback of the detector, the active lighting module will adjust the intensity of LED to provide a steady illumination. Moreover, the module could replace the backlight module of LCD TV when the house has Natural Light Guiding System for saving energy and higher performance of image.

Design and Evaluation of Natural Light Guiding System in Ecological Illumination of Traffic Tunnel

Ecological traffic tunnel means that the manner can deal with tunnel project environmental problem of surrounding area and it is most close to the green environment. In general, we always use artificial light sources, such as traditional light sources and LED, to be the light source of illumination in the traffic tunnel. However, the best light source for the health of the human body is the natural light. If we can guide the sunlight into the tunnel to be lighting source, it would have a great benefit to the health of the human body. In this paper, we use Natural Light Guiding System to provide ecological illumination in traffic tunnel. The system has collecting, transmitting, and lighting parts. In the collecting part, we utilize a static concentrator to collect sunlight which is made up of a prismatic and cascadable unit. In the transmitting part, the collected sunlight is guided by optical fiber or lightpipe efficiently. In the lighting part, we design a lighting module of road lamp for lighting the inside the tunnel. The lighting module redistributes light to conform the traffic regulation. Finally, we build a model of traffic tunnel in optical software with Natural Light Guiding System to simulate the performance.

Heliostat design for the daylighting system

The daylighting system is designed to guide sunlight into buildings for illumination. It has the best illumination performance when sunlight vertically impinges on the collector of the daylighting system, while it has low performance when sunlight impinges obliquely. To overcome the problem, this paper investigates the design of a heliostat that reflects sunlight vertically onto a daylighting system. This study proposes a 3×3 mirror matrix heliostat, which is different from the traditional heliostat with one single mirror. With the heliostat, the system efficiency increases as high as 3.32 times.

Design and Analysis of Natural Light Guiding CPC Structure Used for Indoor Illumination

We have designed an optical component to collect sunlight for indoor illumination. We use a CPC structure utilizing the edge-ray principle to design the collecting part to gather sunlight at many different angles, without a sun tracking system. The CPC structure was designed with the sun condition in Taipei each season. For the maximum efficiency, we define two conditions to evaluate the static concentrator is total energy saving in the visible range.