Engineering topics

Ibbetson, James

Publications and source records attributed to Ibbetson, James.

4 records

DOE OSTI2019

Luminaire with controllable light emission

A luminaire includes a first waveguide having a first primary light emitting surface directed in a first direction and a first secondary light emitting surface directed in a second direction. A second waveguide having a second primary light emitting surface directed in the second direction and a second secondary light emitting surface directed in the first direction. A first plurality of LEDs are optically coupled to the first waveguide and a second plurality of LEDs are optically coupled to the second waveguide. The first and second waveguides are independently operable. The first and second plurality of LEDs may comprise LED groups where each of the LED groups are independently controllable. The light emission pattern and light properties of the emitted light are controllable.

Girotto, Claudio↗

DOE OSTI2017

Solid state lighting component

An LED component according to the present invention comprising an array of LED chips mounted on a submount with the LED chips capable of emitting light in response to an electrical signal. The array can comprise LED chips emitting at two colors of light wherein the LED component emits light comprising the combination of the two colors of light. A single lens is included over the array of LED chips. The LED chip array can emit light of greater than 800 lumens with a drive current of less than 150 milli-Amps. The LED chip component can also operate at temperatures less than 3000 degrees K. In one embodiment, the LED array is in a substantially circular pattern on the submount.

36 MATERIALS SCIENCE↗

DOE OSTI2017

Materials and Designs for High-Efficacy LED Light Engines

Cree, Inc. conducted a narrow-band downconverter (NBD) materials development and implementation program which will lead to warm-white LED light engines with enhanced efficacy via improved spectral efficiency with respect to the human eye response. New red (600-630nm) NBD materials could result in as much as a 20% improvement in warm-white efficacy at high color quality relative to conventional phosphor-based light sources. Key program innovations included: high quantum yield; narrow peak width; minimized component-level losses due to “cross-talk” and light scattering among red and yellow-green downconverters; and improved reliability to reach parity with conventional phosphors. NBD-enabled downconversion efficiency gains relative to conventional phosphors yielded an end-of-project LED light engine efficacy of >160 lm/W at room temperature and 35 A/cm2, with a correlated color temperature (CCT) of ~3500K and >90 CRI (Color Rending Index). NBD-LED light engines exhibited equivalent luminous flux and color point maintenance at >1,000 hrs. of highly accelerated reliability testing as conventional phosphor LEDs. A demonstration luminaire utilizing an NBD-based LED light engine had a steady-state system efficacy of >150 lm/W at ~3500K and >90 CRI, which exceeded the 2014 DOE R&D Plan luminaire milestone for FY17 of >150 lm/W at just 80 CRI.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS1993

Photoluminescence from narrow InAs-AlSb quantum wells

We report on photoluminescence spectra from narrow InAs-AlSb quantum wells. Strong, clearly resolved peaks for well widths from 2 to 8 monolayers were observed. Transmission electron micrographs show direct evidence for the structural quality of the quantum well structures. The transition energies of the narrowest wells suggest a strong influence of the AlSb X-barrier on the electronic states in the conduction band.

Brar, Berinder↗