This PDF file contains the front matter associated with SPIE Proceedings Volume 7059, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

LED light sources are finding ever increasing application in illumination. LEDs have many advantages, such as high efficiency, long life, compactness, directional light emission, mechanical resistance, low-temperature operation, light color control and low UV or IR emissions. These and other advantages make them very well suited for general illumination applications as well as flashlights, car headlights, backlights, or frontlights. In most applications, LEDs are combined with optics to direct their light output. Brighter LEDs have a smaller emission area and, therefore, may be coupled to smaller optics. This is very important in many applications where compactness is crucial, particularly automotive headlamps. When LED brightness is insufficient, it can be augmented by recirculating part of the emitted light back to the LED's emitting surface. This increase in brightness comes at the expense of a reduced flux-emission. As an example, the brightness of an LED with a diffuse reflectivity of 70% may be increased by nearly that much if it is coupled to a high-efficiency recirculating optic. Such augmentation, however, comes at the expense of a flux reduction, as much as 50%. Several optical geometries are explored in this paper to achieve that recirculation together with raytracing results using on a simple model of an LED. Also a number of optical architectures will be shown that escape the classical nonimaging etendue limit associated with traditional optics.

In the design of high-temperature chemical reactors and furnaces, as well as high-radiance light projection applications, reconstituting the ultra-high radiance of short-arc discharge lamps at maximum radiative efficiency constitutes a significant challenge. The difficulty is exacerbated by the high numerical aperture necessary at both the source and the target. Separating the optic from both the light source and the target allows practical operation, control, monitoring, diagnostics and maintenance. We present near-field unfolded aplanatic optics as a feasible solution. The concept is illustrated with a design customized to a high-temperature chemical reactor for nano-material synthesis, driven by an ultra-bright xenon short-arc discharge lamp, with near-unity numerical aperture for both light input and light output. We report preliminary optical measurements for the first prototype, which constitutes a double-ellipsoid solution. We also propose compound unfolded aplanats that collect the full angular extent of lamp emission (in lieu of light recycling optics) and additionally permit nearly full-circumference irradiation of the reactor.

The tolerancing of optical devices is of importance in many industrial applications. Illumination devices that produce a cut-off line in the light distribution are examples where demanding requirements have to be met. The approaches that will be presented are used as a prerequisite to make these illumination devices more robust, i.e. relatively insensitive to position tolerances and to adverse conditions under which they have to be operated. Emphasis will be laid on LED optics that feature high optical efficiency. The method of optical transfer matrices represents a convenient tool to study optical devices in a paraxial approximation. The results of such calculations also provide a guideline on how to plan the numerical simulations. This is helpful, because the simulations that have to be performed in this branch of illumination engineering are quite time-consuming. To sum up the simulation results abstract representations will be used. They are considered helpful to keep the overview in a wealth of data gained by automated simulations and to communicate them in a concise way. Tolerancing within tight requirements prescribed by legislation for safety reasons, as it is typical for frontlighting applications, will be addressed.

Beam shaping of incoherent light sources (LEDs, halogen lamps) for arbitrary target light distribution is obtained by a single free-shape mirror. Special design algorithm ensures continuous profile without abrupt changes and shadowing regions. The mirror is manufactured by single point diamond turning combined with Fast-Tool-Servo (FTS) for simultaneous figuring of base surface and fine structure (for redistributing the light energy). Lateral and axial resolution of the fine structure is determined by FTS and considered during the design and data transfer. Directly turned surfaces can be used as replication tools for polymer or glass moulding and embossing.

The importance of condenser optics is the fact that it is the bottleneck limiting efficiency in commercially available projection systems. Efficiency is a key parameter of projector performance, since it augments screen luminance, enabling the system to perform well under increasing levels of ambient light. Conventional condensers use rotational symmetric devices, most of them being elliptic or parabolic mirrors. They perform very far from the theoretical limits for sources such as arc lamps or halogen bulbs. Typical small displays in the 5-15 mm² etendue range have geometrical efficiencies about 40-50% for the best condensers; although theory allows about 100% (no reflection nor absorption losses are considered). The problem is in the coma aberration of the reflectors and the rotational symmetric image of the source making the source projected image to unfit with the target. Thus, the only way to improve this performance is to generate a free form design that is able to control the shape and rotation of the source projected images. As yet, this can only be done with the SMS3D design method. We present here two of such designs types; one of them achieving a geometrical efficiency that is 1.8 times that of an elliptical condenser for a 4:1 target aspect ratio and for the range of target etendue with practical interest and 1.5 for 16:9 target. The other design type is more adequate for circular targets and gets a geometrical efficiency up to 1.4 that of an elliptical condenser. These designs use only 1 additional reflection, i.e., use a total of 2 reflections from the source to the target. A prototype of one type of free form condenser has already been built.

Today numerical simulation is a major tool in the design process of non imaging illumination sources. The numerical simulation is in use for different integration levels of light sources, where various numbers of design parameters exist. A variation of all available parameters leads to high amount of samples, which must be simulated and analysed. To reduce the number of variants, a statistical relevant number of samples are used. For this purpose the methods of DoE (Design of Experiments) are applied. In connection with computational methods, the simulation process itself could be automated. This leads to a very efficient design process for non imaging illumination systems. Main challenges are the parameter definition for the DoE, the design of the automated process, and a correct approximation of the achieved result. After solving of all challenges, an efficient system for the prediction of the technical parameters of new illumination is created. This paper describes the general problem of variant analyses and the achievements in automatic DoE studies for illumination systems. An outlook shows how this method could be beneficial in the design process of daylight systems.

A new free-form XR Kohler concentrator is presented that combines high geometric concentration, high acceptance angle and high irradiance uniformity on the solar cell. This is achieved by modifying the optical surfaces to produce Kohler integration. Although the new optical surfaces (that is, the ones including Kohler integration) behave optically quite different from the ones that do not integrate, but from the macroscopic point of view they are very similar to them. This means that they can be manufactured with the same techniques (typically plastic injection molding or glass molding) and that their production cost is the same i.e., with a high potential for low cost and high optical efficiency. The present approach is completely new and allows keeping the acceptance angle at high values and the concentration factor without increasing the number of optical elements. The simulated optical performance of a Kohler integrating solar concentrator is presented. This concept is the first design combining non flat array of Kohler integrators with concentration optics.

A novel photovoltaic concentrator is presented. The goal is to achieve high concentration design with high efficiency and high acceptance angle that in the same time is compact and convenient for thermal and mechanical management [1]. This photovoltaic system is based on 1 cm² multi-junction tandem solar cells and an XR concentrator. The XR concentrator in this system is an SMS 3D design formed by one reflective (X) and one refractive (R) free-form surfaces (i.e., without rotational or linear symmetry) and has been chosen for its excellent aspect ratio and for its ability to perform near the thermodynamic limit. It is a mirror-lens device that has no shadowing elements and has square entry aperture (the whole system aperture area is used for collecting light). This large acceptance angle relaxes the manufacturing tolerances of all the optical and mechanical components of the system included the concentrator itself and is one of the keys to get a cost competitive photovoltaic generator. For the geometrical concentration of 1000x the simulation results show the acceptance angle of ±1.8 deg. The irradiance distribution on the cell is achieved with ultra-short homogenizing prism, whose size is optimised to keep the maximum values under the ones that the cell can accept. The application of the XR optics to high-concentration is being developed in a consortium leaded by The Boeing Company, which has been awarded a project by US DOE in the framework of the Solar America Initiative.

Writing optimization code for commercially available ray-tracing software, we explore variations of concentrator geometry where sunlight is first incident onto a stationary primary mirror of circular cross section. The reflected light is incident onto a smaller, secondary moveable mirror which focuses the light onto a target. Simulations show concentrations on the order of 30 solar equivalents are possible.

We show that an aplanatic imaging system can approach theoretical maximum concentration limit following a brief review of Abbe Sine condition and aplanatism. We use a two-mirror case to demonstrate how to construct such aplanatic systems using Luneburg method. The result is useful in designing high-performance concentrators.

We investigate the parametrical scaling of LED collimators with folded multiple reflections, described by rational Bezier spline. One can scale the collimator linearly with source size (maintaining residual divergence). Scaling factor should be calculated from etendue conservation if one needs to scale the collimator for a different residual divergence. Both up- and downscaling the collimator (reducing the collimator diameter to obtain the design with larger divergence and vice versa) are considered. Concentrator shape cannot be linearly scaled if we change the material (for example polycarbonate is used in design instead of PMMA). Method allows rapid development of collimating optics.

Since the invention of the flashlight in the late nineteenth century, it has proven indispensable for both civilian and military use. To date, the prevailing optical element used for collecting and concentrating light from the source has been the paraboloidal reflector. The advent of LED light sources, recent theoretical developments in nonimaging optics and advances in polymer optics are revolutionizing flashlight optics. We present new classes of optical solutions that provide superior efficiency, beam shaping, and active beam control. These solutions are patent pending.

This paper documents the development and demonstration of a solid-state NVIS-friendly visible and near-IR external lighting system modification for the KC-135. The system addresses current needs of tanker aircraft during night air-toair refueling operations, and consists of solid-state visible and near-IR light-emitting diode based programmable replacements for selected existing incandescent lights on the exterior of the aircraft. The system utilizes a novel means of controlling output modes from light fixtures, is rapidly installable at the unit level, and entails only form-fit replacement of existing controls and light fixtures while utilizing only existing mounting provisions and wiring in the aircraft. Although the current design is specific to the KC-135, the system principle is applicable for installation or retrofit to any aircraft. The genesis of the concept, component design, integration on a KC-135 test aircraft platform, and the results of ground demonstration assessment are described.

A conventional backlight unit (BLU) is used to as the light module to present uniform light of liquid crystal display (LCD). In general, cold cathode fluorescent lamp (CCFL) is utilized to be the light source of BLU. The light emitting diode (LED) is now considered well known as a promising device for solid state lighting. It has the advantages of long durability, no mercury substance and good endurance of heavy impact. To satisfy the market demands of the thin-film liquid crystal display (LCD) and the green product, the LED is applied to as the light source to make display thinner, lighter, no Hg containing. In this research, the LED uniform lightguide is demonstrated because it enables the point-like light to distribute propagating-light line pattern successfully. By optimizing the size and the radian of the device, the designed LED uniform lightguide can achieve the output efficiency more than 85%, and its illuminative uniformity is improved about 85%. Thus, the LED uniform lightguide not only can decrease the number of LED to save the space, but also enhance the optical efficiency. In the future, a novel LED uniform module could make displays thinner and lighter for backlight system applications.

Design and evaluation of new illumination system utilizing white light emitting diode (LED) and plastic light-guide for letter-size (216mm width) document scanner and copier have been performed. We investigated the best condition for illumination on document plane through the optical analysis of scanner imaging system. To compensate the relative illumination fall-off caused by imaging lens, illumination on main-direction was designed to edge enhanced distribution. The illumination on sub-direction was designed to flat-top shape for stable performance against mechanical displacement of optics. The light-guide was designed dual-angled sidewalls for the decrease of light leakage and the increase of the degree of freedom for illumination shaping. The rear area of a light-guide is formed with crossed micro-prism patterns to axial direction to induce scattering of guided light, and the front area is formed with lens-shape for efficient lighting. Total 12 parameters were used for the optimization of design, and the various relationships between parameters and performances were also investigated. The optical characteristics of the proposed illumination system utilizing a white LED and light-guide, fabricated by mold process, were also experimentally evaluated in terms of illumination distribution against main- and sub-direction on image plane. They showed excellent agreement with simulated result and showed good performance of uniformity above 91%, and 89% in sub-direction and main-direction, respectively.

We provide a novel scheme in designing no-loss bent light-pipe with the help of a transformation of elliptical form on equiangular spiral.

We propose two types of light pipes, namely wedge and circular forms, the incident direction of light propagation could be rotated as necessary while still preserving beam polarization. We also deduce the basic conditions of these preservations of polarization. Several typical cases of light pipes are analyzed by numerical simulation. As one of the examples, it is verified that a collimated beam with +45 degree linearly polarization can be guided to any pre-settled direction where the ellipse ratio variation in polarization is less than 0.1%.

In this work we report on a non-imaging optical concentrator for high-speed polymer optical fiber (POF), which has applications in chip-to-chip, consumer display, and backplane data transport. High-speed operation places demands on the ability of coupling from large-core media to small apertures typical of 10 Gbps optoelectronics. Design and fabrication of concentrators made by single point diamond turning and injection molding will be discussed, and comparison of experimental data to simulation will show good coupling efficiency with a wide tolerance to fiber misalignment.

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.

We have designed optical structure to be used as tiles on the outsides of buildings for indoor illumination. To cover an entire building, we have designed optical units to be used together that can compress light. The important factor in our design is producing parallel exit beam from our single units. We have used saw-toothed surface with two different principles, the Co-focus and Parallel-plate, to design optical units. Finally, we analyze the efficiency and the beam divergence angle to compare these optical structures.

For a wide application area, LEDs are always with secondary optic elements for a specific characteristic. However, the secondary optic element has two serious phenomena, die-imaging and yellow hue. In this literature, we study the two phenomena in two parts. The first part focuses on the relationship between the die-imaging phenomenon and the imaging power of TIR lens. In this part, we design two TIR lenses, point-to-point and point-to-plane, with difference imaging power and analysis the ray paths. The second part focuses on the simulation of white LED with the two different TIR lenses to study yellow hue phenomenon. Based on the color difference in CIE (u', v') picture, we get the relationship between refractive power and color shift. Finally, we adopt the MacAdam ellipsis system to define the reasonable color gamut.

We present a static concentrator system made up of refractional units for changing slanted sunlight to vertical light. The refractional units are cylindrical and were placed to face the sun over Taipei. We used meteorological data from the Central Weather Bureau in Taipei to define the collecting range of our system. Based on the vignetting effect and the loss of sunlight, we discuss the configurations of refractional units and compare their performances. For evaluating the performances, we define a parameter to evaluate the refracting capability.

We have studied designs of an edge-lit backlight that can switch its emission angle range between a narrow and a wide state. Here, we propose three types of output couplers for this type of backlight unit. These are quadratic prism, triangular prism and arc prism. The probability of extracting the light propagating inside a light-guide does not depend on its propagation angle for each of these output couplers. We conducted ray tracing analysis to compare these output coupler designs. The results show that approximately 65% illumination uniformity and 75% efficiency can be obtained with the quadratic prism. For each setting of the emission range, the width of the angular distribution is switched between 30 and 102 degrees (FWHM). Other two output couplers perform poorly in terms of these optical properties.

Transmission of light through a 90 degrees elbow in a hollow light guide is an important step in the development of natural lighting applications. In this paper we present a new design that has more than 260% higher efficiency in flux transfer than a standard bending system for hollow and aluminum light guides. The clue of this new system is to minimize the light angle at the output of the elbow, in such way that it is possible to guide light at higher distances because of the fewer reflections in the light guide. The system works properly for prismatic light guides but is also suitable for aluminum guides where the reduction of reflections permit the use of cheaper aluminum or the increase in length maintaining flux transfer. Also this reduction of reflections in aluminum light guide derives in less change of chromatic coordinates.

This study proposes a generation scheme for the light guide of the edge-lit backlight using a microstructure with a pattern combining variable aspect ratio and a variable microstructure orientation, based on the molecular dynamics method of a generalized force model. This generation scheme is necessary to accommodate the need for the subsequent optical design phase, and allows for easier optical optimization for the microstructure distribution in order to reach the equal luminance condition. These needs are met by the cell division, which allows the adjustment of the microstructure density in each sub-domain, or cell. The boundary treatments allow the precise control of the microstructure density in each cell and the ability to smooth the microstructure distribution across the cell boundary. Finally, the performance of this generation scheme, as well as a practical example combining this scheme with the optical design, is shown and discussed.