Realizing freeform lenses using an optics 3D-printer for industrial based tailored irradiance distribution

This paper presents a three dimensional lens shaping method for dual-LED packaging module using silicon micromachined substrate. The technology utilizes flower-typed structure and silicone dispensing process to fabricate a 3-D freeform encapsulation lens for achieving uniform illumination and specific light pattern. Based on the experimental results, with the size of 2×4 mm2 of the flower-typed island, the freeform lens is formed with a sag height of 2.7 mm when the dispensing volume is 15 mm3. On the measurement, the projected light pattern is obvious that the light distribution is similar to a rectangular shape, with a good uniformity.

Light flux from LED must be redistributed to meet the needs of lighting in most cases, a new method is proposed for its secondary optic design. Based on refractive equation and energy conservation, a set of first-order partial differential equations which represent the characters of LED source and desired illumination were presented. The freeform lens was constructed by solving these equations numerically. The numerical results showed that we can get a freeform lens for the illumination of uniformity near to 90%, with considerable high computation speed. This method can shorten the designing time of the freeform lens with high accepted tolerance.

An optimization method is proposed for designing an LED freeform lens which produces a uniform circular pattern with high energy efficiency. This method is composed of three main aspects: design of the initial guess, parameterization of the freeform surface, and construction of the merit function. The initial guess is created by solving an ordinary differential equation numerically. An approach of selecting optimization points is introduced for parameterization of the freeform surface. The merit function is constructed by use of the irradiance uniformity and the efficiency of the lens. Design examples are given, and the results show that the irradiance distribution is well controlled with a maximum uniformity (the relative standard deviation of irradiance, RSD) of 0.0122 and a maximum efficiency of 93.88%. This optimization method can be generalized to design freeform lenses with different lighting patterns or without rotational symmetry.

Design of double freeform-surface lens for LED uniform illumination with minimum Fresnel losses

Traditional surgical shadowless halogen lamps are generally designed as projection type with many light bulbs, which can produce not only mercury pollution but also heat radiation that are serious problems to patient. The study utilized Runge‐Kutta methods and mathematical algorithms to design and optimize the freeform lens. The LED (light‐emitting diode) was adopted to replace the traditional halogen lamp. A uniform lens was designed and fabricated based on the energy conservation. At first, the light field of LED is concentrated through the freeform lens to improve the optical efficiency. Second, the three‐shell elliptic curves are applied to the reflective surgical shadowless lamps, where only few LED chips are needed. Light rays emitting from different directions to the target plane can achieve the goal of shadowless. In this study, the LED’s luminance flux is 1,895 lm. The shadow dilution on the target plane is 54%. Ec (central illuminance) is 114,900 lux, and the d50/d10 is 57% which is higher than the regulation by 7%, whereas the power consumption is only 20 W. The energy of reflective surgical shadowless lamps can save more than 50%, compared with the traditional projective one.

Ink-jet printing (IJP) technology is a popular technology for desktop publishing. Since some of the conducting polymers are solution processable, IJP technology becomes an ideal method for printing polymer light-emitting diodes with high resolution. In this manuscript, we present the first successful demonstration of patterning the polymer electroluminescent devices using the IJP technology. Unfortunately due to the dot form printing by the IJP, the polymer film printed from an ink-jet printer consists of pin-holes. This makes it unsuitable for fabricating high quality polymer electronic devices, particularly for devices in the sandwich structure. In this paper, we submit a hybrid structure, which consists of an ink-jet printed layer in conjunction with another uniform spin coated polymer layer, as an alternative to the regular ink-jet printed structure. The uniform spin coated polymer layer, as an alternative to the regular ink-jet printed structure. The uniform layer serves as a buffer layer to seal the pin hoe.s and the IJP layer is the layer consisting of the desired pattern, for example the red-green-blue dots for a multicolor display. To demonstrate, we applied this hybrid technology to fabricate efficient and large area polymer light-emitting logos. The use of this concept represents a whole new technology of fabricating polymer electronic device with lateral patterning capability.

In many applications, the emitting light from light-emitting diodes (LEDs) with different colors needs to be mixed together on a large-scale plane, and this illumination mode is usually generated with a diffuser. Abandoning the traditional methods, we proposed an LED color-mixing method that can produce both high color uniformity and irradiance uniformity illumination. This method is composed of two main aspects: arrangement of the irradiance array and design of the LED lens. With this method, an independent rectangular irradiance distribution is generated by each lens unit, and the large-scale color uniform illumination is obtained by arraying the irradiance distribution. A 3×3 array of LED module units consisting of 36 LED lens units with four different colors is designed, and a desired result with high color uniformity is obtained.

The reflector of one surface for Light-emitting diode (LED) is designed based on flux compensation method. It is easier to be fabricated compared with freeform lens. Moreover, the reflector can effectively reduce material absorption loss. This design method is simple and other researchers can understand and repeat more simply. The designed reflector also has a small exit angle for uniform illumination. It has high illuminance uniformity and flux efficiency, which are more than 90% and 95%, respectively. Reflectors designed here can be used in optical signal coupling, display cabinets, and other optical transmission applications.

The ink jet printing (IJP) technology of organic conducting inks to be applied to the fabrication of conducting films has been demonstrated. Conducting films of (3,4-ethylenodioxythiofene)/poly(4-styrenestilfonate)-PEDOT/PSS and glycerol-modified PEDOT/PSS were deposited on different kind of plastic substrates using the ink jet printing technique. Electrical resistance measurements and atomic force microscopy (AFM) images of these conducting films were realized and a brief comment is made about their application in electric-field probes.

Inkjet and screen printing technologies are well known in the graphic arts industry for the reproduction of texts, images, and graphics. During the last decades, these printing technologies have been attracting increasing interest for the deposition of functional materials, e.g., in the field of printed electronics and for biological applications. However, their usage is mainly limited to 2D applications, i.e., rather flat deposits ranging from nanometers to several tens of micrometers in thickness. For 3D applications, sophisticated additive manufacturing technologies are developed to manufacture structures with high shape complexities. Herein, the potential of standard inkjet and screen printing technology as tools for the development of functional 3D objects is demonstrated. 3D functional structures printed by inkjet and screen printing technology combining conductive and nonconductive materials to a multi‐material structure are shown. A metal nanoparticle ink formulation is applied to inkjet‐print conductive metal pillars with a high aspect ratio (in the range of 50) used as vertical interconnects. The interconnects are encapsulated with an inkjet‐printed polymeric ink formulation and finally used as conductive tracks to light up a solid‐state light‐emitting diode (LED). Screen printing is applied to print primary batteries used as the power source for the LED.

This study details a one-time ray-tracing optimization method for the optimization of LED illumination systems [S.-C. Chu and H.-L. Yang, "One-time ray-tracing method for the optimization of illumination system," in Proceedings of International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN, 2013), 87692M]. This method optimizes the performance of illumination systems by modifying the light source's radiant intensity distribution with a freeform lens, instead of modifying the illumination system structure. Because illumination system structures are unchanged in the design process, a designer can avoid the common problems faced when designing illumination systems, i.e., the repeated and time-consuming ray-tracing process when optimizing the illumination system parameters. The easy approaches of the proposed optimization method to sample the target illumination areas and to divide the light source radiant intensity distribution make the proposed method can be applied to both direct-lit and non-direct-lit illumination systems. To demonstrate the proposed method, this study designs an illuminator for a tube photo-bioreactor using the proposed one-time ray-tracing method. A comparison shows that in the designing of the photo-bioreactor, tracing all rays one time requires about 13 hours, while optimizing the light source's radiant intensity distribution requires only about twenty minutes. The considerable reduction in the ray-tracing time shows that the proposed method is a fast and effective way to design illumination systems.

In 5G, indoor visible light communication is going to use panel of white light emitting diodes (LED) to provide high-speed communication as well as illumination. In this system, it is important to maintain uniform illuminance as non-uniformity creates bright and dark spots, which may cause discomfort for the occupants. The uniform illuminance depends upon the position and semi-angle of radiation associated with the LED panel. The objective is to optimize the position of the LED panels so that the received power and SNR at all locations in the room are uniform. The optimization task is carried out using a new metaheuristics whale optimization algorithm. Simulation study is performed in a room with dimension 5 × 5 × 3 m, having 4 to 6 LED panels (each with 60 × 60 LEDs). Results reveal that the proposed approach obtained superior uniformity (received power and SNR achieved in dB) compared to that achieved by particle swarm optimization.

In this study, a novel method for the fabricating silicone lenses is proposed based on ionic wind. In such a method, the normal stress on the air-liquid interface is induced and adjusted by ionic wind, which is applied around liquid lens material. Through adding a specific shape of mask, the lens can be tailored into desired freeform morphology. Experiments are conducted and freeform lens of dual stripe and meniscus shapes are fabricated by configuration of specific mask. Besides, the influence of thickness of silicone gel and the shape of micro-patterns upon optical performance is analyzed by optical simulation, the Monte Carlo ray-tracing method. Results show that the improvement of LEE with the dual stripe lens reached 41.02%.

Nonuniform illumination caused by extended source is one of the challenging points for high power Light-emitting diodes (LEDs) especially for LED array applications. A new design method to improve the uniformity of illuminance of extended source is presented. To obtain high uniformity at target plane, a feedback optimization method is introduced including target plane girds, light source girds and target plane and light source girds optimization algorithms. Monte Carlo ray tracing simulation results demonstrate that our feedback optimization algorithms are able to obviously increase the uniformity of illuminance at target plane. The uniformity increases from 0.53 to 0.9, 0.77 and 0.88 by our three different optimization algorithms respectively. This method would be a potential way in improving the uniformity of illuminance at target plane with little light pattern expansion.

Inkjet printing technology, a maskless, non-contact patterning operation, which has been a revelation in the field of micro and nano manufacturing for its use in the selective deposition of desired materials. It is becoming an exciting alternative technology such as lithography to print functional material on to a substrate. Selective deposition of functional materials on desired substrates is a basic requirement in many of the printing based micro and nano manufacturing operations like the fabrication of microelectronic devices, solar cell, Light-emitting Diode (LED) research fields like pharmaceutical industries for drug discovery purposes and in biotechnology to make DNA microarrays. In this paper, an attempt has been made to design and develop an indigenous Electrohydrodynamic Inkjet printing system for micro fabrication and to study the interrelationships between various thermos-fluidic parameters of the ink material in the printing process. The effect of printing process parameters on printing performance characteristics has also been studied. And the applicability of the process has also been experimentally demonstrated. The experimentally found results were quite satisfactory and accordance to its applicability.