Research topics today
Source: LRC
Requirements for White LED Encapsulants
Encapsulation materials play an important role in the development of reliable, high-efficacy white LEDs. Using materials with a suitable index of refraction can increase the overall light extraction of LED packages. Researchers try to characterize encapsulant materials used and marketed for white LEDs, understand how the refractive index of these materials changes with temperature, and identify the most suitable encapsulant properties for the highest extraction efficiency.
Color Uniformity Improvement of Mixed-Color LED Systems
RGB LED mixing is a promising method to produce white light because of its high efficiency. However, one problem with this method is color uniformity. A mixed beam often shows a white center surrounded by colorful edges. An object placed between RGB light sources and a white screen produces colorful halos around the shadow of the object on the screen. Researchers will look for a solution without sacrificing efficiency. The proposed method combines SPETM(Scattered Photon Extraction) technology and a micro-sphere doped diffuser. SPETM technology has been shown to increase LED efficiency, while the micro-sphere doped diffuser can mix light from RGB LEDs to achieve better color uniformity. The combination of the two potentially could improve color uniformity in RGB systems without sacrificing efficiency.
White LED Cylinder Lamp
Researchers are investigating the development and performance of a white LED cylindrical source using remote phosphor technology. The study will focus on the parameters related to the source's extraction efficiency.
LED Thermal Management Using Nanomaterials
Researchers explore the use of nanomaterials to manage the heat in high-power LEDs. Because the increasing power density of high-power LEDs requires more efficient heat dissipation, large heat sinks are necessary to ensure their performance and reliability. Presently, LEDs have high thermal resistances (see the LRC’s study on Characterizing the Thermal Resistance Coefficient of LEDs for more on this concept). A lower thermal even resistance would help relieve the heat problems faced by many high-power dies, allowing for higher power operation to produce more light.
Investigating the Optical Properties of Phosphor to Improve White LED Performance
Researchers explore the transmission, reflection, and absorption characteristics of YAG:Ce phosphor used in white LEDs. Laboratory experiments are being conducted to understand the wavelength dependency of these characteristics as a function of phosphor density. Knowing how different wavelengths of light interact with the phosphor allows for more accurate modelling of remote phosphor white LED packages, and thus allows for further improvement in light output and color properties.
Applied and Field Research
Development of an Energy-Efficient, Ultra-Thin LED Luminaire
Researchers will determine the feasibility of developing an energy-efficient, ultra-thin LED-based luminaire that will effectively replace downlights, accent lights, and wall-wash luminaires using incandescent and halogen technologies and allow energy-efficient lighting to be used in a wider array of applications than is possible with current technologies.
Novel Microlens Materials for Beam Control in Thin-profile LED Luminaires
Researchers will advance the development of microlens materials for beam shaping. The lens materials will be used in the development of an ultra-thin LED luminaire.
Electronic Walls and Ceilings Offer Adaptable Solid-State Lighting
Research & development a flexible interior infrastructure that will integrate solid-state lighting with other building materials and systems. The design includes interchangeable, modular panels with integrated LED lighting fixtures that are part of an electrical network
Metrics and Measurement Procedures for LED Lighting Systems
Research of new metrics and measurement methods related to LED systems
Detectability of LED Fixtures with IR Cameras
Research to identify the required infrared (IR) signature, wavelength, and minimum energy in that wavelength band in order to develop solutions that would enable the detection of LED systems with IR cameras.
Metrics for LED Lighting Brightness
The standards and metrics that are used with traditional lighting may not work well for LEDs, particularly in the area of brightness perception. For example, a green LED approach light may be perceived as too bright compared with a green incandescent light of the same luminance. Researchers will develop an initial recommendation that can be used to specify the luminous intensities for LED signal lights that will result in equivalent brightnesses as incandescent signal lights.
Investigation of Thermal Management in Blue LED Taxiway Lights
On airport runways, blue light fixtures denote taxiways between the runway and the airport terminal. Blue optics transmit mostly short-wavelength radiation, which makes traditional incandescent lamps a poor choice of light source; the resulting fixture efficiency is less than one percent. LEDs are replacing incandescent lamps in this application, but unlike incandescent sources, LEDs do not radiate enough heat to melt ice and snow from the fixture optics. To meet regulations for weather ability, some LED-based fixtures incorporate heaters that, when switched on, nearly negate the energy-savings benefit of converting to LED sources. Researchers will explore methods for conducting and convecting LED junction heat to taxiway fixture optics. The feasibility of heating taxiway fixture optics with LED heat to optimize fixture efficiency will be examined.
