Lighting Research Center Lighting Research Center
Scattered Photon Extraction (SPE)

SSL Recent Projects

Research Categories

Applications and Demonstration
Human Factors
Performance, Metrics and Test Methods


Applications and Demonstration

LED Lighting for Multi-family Housing  
The LRC and ASSIST have published a guide for multi-family housing owners and facility managers on how to upgrade to LED lighting.

Electronic Walls and Ceilings Offer Adaptable Solid-State Lighting
Solid-state lighting offers new ways to think about how we light our spaces. The LRC has developed a flexible interior infrastructure that integrates solid-state lighting with other building materials and systems, allowing for rapid reconfigurations of built-in lighting.

LED Replacement for Linear Fluorescent Lamps pdf logo
The LRC investigated solutions for and built a prototype of an LED replacement for 4-foot linear T8 fluorescent lamps using remote phosphor technology.

LED Systems for Greenhouse Plant Lighting pdf logo
The LRC investigated the potential use of LED lighting systems for plants grown in greenhouses.

Designing a Better Recessed Downlight Using SPE Technology
The LRC developed a highly efficient LED downlight to replace an equivalent 75W incandescent or 26–32W CFL downlight.

Efficiency Testing for Freezer Case Lighting 
Current industry practice rewards freezer lighting for its luminaire efficacy measured at room temperature. To obtain realistic data, the evaluation method must consider the application environment. ASSIST has published a technology-neutral method for evaluating the performance of luminaires used in freezer cases.

Snap-In LED Module for Outdoor Luminaires
LRC researchers developed an energy-efficient, snap-in LED module for lighting systems using the LRC’s patented scattered photon extraction (SPE) technology. Each individual module can be easily fixed or disassembled from the luminaire as needed.

Standalone PV-LED Lighting for Aviation
The LRC conducted a study to understand the factors that affect the performance of standalone PV-LED lighting systems, especially how the charge controller affects total system performance.

Development of an Energy-Efficent, Ultra-thin LED Luminaire
The LRC explored a novel "ultra-thin" LED luminaire concept to replace downlight, accent, and wall-wash luminaires using incandescent and halogen technologies.

LED Blue Taxiway Luminaires
The LRC explored new luminaire designs and methods of transferring heat from the LED junction to the optics in order to minimize snow and ice buildup on blue airport taxiway luminaires.

Remote Airfield Lighting Systems
Many remote communities, such as those in Alaska, depend on air transport for business and emergency aid. Night landings at remote airfields are often dangerous. The LRC explored ways to help make night landings at remote airports safer and area communities more accessible.


Human Factors

Effect of Colored Luminous Surrounds on LED Discomfort Glare pdf logo
The LRC investigated the connection between discomfort glare perception and the SPD of a luminous area surrounding a white LED array, taking into consideration the luminous surround spectrum, brightness perception, and the effect of a luminous surround on an LED array glare stimulus.

Perceptions of White Light Sources of Different Color Temperatures  
The Lighting Research Center and ASSIST conducted a series of experiments to measure perceptions of white illumination from light sources of different CCTs.

The Potential of Outdoor Lighting for Stimulating the Human Circadian System 
The Lighting Research Center and ASSIST sought to provide a quantitative analysis of the impact of light at night, particularly from streetlights of different spectral power distributions, on the human circadian system.

Redefining White Light Chromaticity Boundaries for Aviation
The LRC conducted a human factors investigation of the boundaries in chromaticity space that people perceive as white and recommended new aviation white boundaries that were independent of the color limitations of incandescent sources.

Requirements for Runway Guard Lights pdf logo
The LRC conducted laboratory human factors experiments to determine the appropriate luminous intensity and other operating parameters of LEDs used in runway guard lights in order to provide acceptable visibility and safety.

LED Aviation Signal Brightness
LED signal lights have narrower spectral distributions than incandescent (filtered and unfiltered) signals, resulting in more saturated colors. Since color saturation increases the perception of brightness, the Federal Aviation Administration (FAA) asked the LRC to develop a set of “brightness correction factors” for white, green, and blue signal lights.


Performance, Metrics and Test Methods

Degradation of LED Encapsulants pdf logo
This study evaluated the effects of short-wavelength radiation and thermal stress on the degradation of an epoxy LED encapsulant, with and without phosphor in the medium.

Long-term Evaluation of LED Airfield Luminaires pdf logo
LRC researchers conducted a long-term performance evaluation of LED airfield luminaires under operating temperatures that covered a range of realistic conditions, as a first step toward establishing a functional definition of useful life for these lighting systems.

Managing Heat in the LED System’s Remote Phosphor Layer pdf logo
LRC researchers investigated methods to reduce the operating temperature of the remote phosphor layer and the resulting effects on LED performance.

Measuring LED Lens Surface Temperature with Thermocouples  pdf logo
The LRC conducted a study to understand the problems in using thermocouples to measure LED lens surface temperature and to find a solution to improve measurement accuracy.

Predicting LED System Failure through Real-time Changes pdf logo
This study sought to identify electrical and thermal parameters in a single-die InGaN LED package that could give real-time signals of impending failure while in use.

Reducing Flicker from AC LEDs  pdf logo
LRC researchers sought to create a new circuit design for AC LEDs with targeted benchmarks to ensure acceptable flicker levels and system performance.

Dimming Behaviors of LED Replacement Lamps  
LRC researchers investigated the dimming performance of commercially available LED and CFL replacement lamps and the performance variations among different dimmers. Human factors experiments were then designed to determine users' expectations for lamp dimming, which became the basis for ASSIST's technology-neutral lamp dimming recommendation.

Minimizing Flicker from SSL Systems  
To assess the ability of individuals to perceive light source flicker directly and indirectly, and to understand the role of flicker characteristics on comfort, the LRC conducted laboratory studies under flickering patterns differing in frequency, modulation depth, duty cycle and waveform shape.

Techniques to Improve Green Phosphor for Superior White LEDs
LRC researchers investigated a “green” phosphor for its performance and ability to improve the efficacy and color of a white LED.

Estimating the Junction Temperature of AC LEDs
LRC researchers developed an alternative method of estimating AC LED junction temperature and thermal resistance.

White SPE LEDs with Multi-phosphor Layers
Recent LEDs have improved their color properties by combining multiple phosphors instead of using a single yellow phosphor. The common practice is to create a random mixture of multiple phosphors that is spread around the LED chip. In this study, LRC researchers questioned the impact of randomly mixing the phosphors versus stacking different phosphors in layers, as well as the effect of the order of the layers.

Accelerated Life-test Method for LED Drivers 
The LRC conducted a study to understand what factors influence the failure modes of standalone LED drivers, and to develop an accelerated test method to predict the useful life of an LED driver.

Optimizing Remote-phosphor LEDs with Optical Ray-tracing
LRC researchers developed a method to determine the MFP of a phosphor layer that can be used in optical ray-tracing analysis to obtain accurate results.

SPETM Technology for Mixed-Color LEDs
The LRC hypothesized that a new approach using SPETM optics with optical diffusers could improve the spatial color uniformity of mixed-color LED systems without sacrificing much efficiency.

Extracting More Light From LEDs
An LED’s efficiency is limited by its inability to extract some of the light generated by the chip’s active layer. One reason for this light loss is the refractive index mismatch between the chip and the surrounding medium. The LRC conducted a two-part study: an optical ray-tracing analysis to understand what factors influence light extraction, and a laboratory study to quantify the refractive indices of commercial encapsulants.


 = ASSIST Project

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