Zobrazeno 1 - 10
of 34
pro vyhledávání: '"Ralph Wirth"'
Publikováno v:
Color Research & Application. 40:287-296
The objective of the present study is the development of an optimized evaluation method which describes color uniformity in the far field of light-emitting diode (LED) spot lights related to visual perception of color and pattern. The merit function
Publikováno v:
Optics Express, ISSN 1094-4087, 2015, Vol. 23, No. 3
Archivo Digital UPM
Universidad Politécnica de Madrid
Archivo Digital UPM
Universidad Politécnica de Madrid
We analyze the color uniformity in the far field of spotlight systems to estimate visual perception with a merit function derived from human factor experiments. A multi-colored light-emitting diode (LED) light engine with different light mixing level
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::fede447180d8bd2175aaab9211a632fd
http://oa.upm.es/43550/
http://oa.upm.es/43550/
Publikováno v:
IEEE Journal of Selected Topics in Quantum Electronics. 8:321-332
This paper reviews the recent progress of AlGaInP high brightness light-emitting diodes. After the discussion of some basic material properties and the general problem of light extraction we will discuss several approaches of high efficiency devices.
Publikováno v:
Proceedings of the SPIE | 13th International Conference on Solid State Lighting | 20/08/2014-21/08/2014 | San Diego, California, EE.UU
Archivo Digital UPM
Universidad Politécnica de Madrid
Archivo Digital UPM
Universidad Politécnica de Madrid
Spotlighting is one illumination field where the application of light emitting diodes (LED) creates many advantages. Commonly, the system for spot lights consists of a LED light engine and collimating secondary optics. Through angular or spatial sepa
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::0c17153faabcce7aa438fc8c0212696d
https://oa.upm.es/36081/
https://oa.upm.es/36081/
Publikováno v:
Proceedings of the SPIE | Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVIII | 01/02/2014 | San Francisco, California, EE.UU
Archivo Digital UPM
Universidad Politécnica de Madrid
Archivo Digital UPM
Universidad Politécnica de Madrid
The scope of the present paper is the derivation of a merit function which predicts the visual perception of LED spot lights. The color uniformity level Usl is described by a linear regression function of the spatial color distribution in the far fie
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::0802cf0ddf20c82076efab184ed50b6e
https://oa.upm.es/36075/
https://oa.upm.es/36075/
Autor:
Ralph Wirth, K. Streubel, S. Illek, Siegmar Kugler, Rainer Butendeich, Reiner Windisch, Heribert Zull
Publikováno v:
IEEE Photonics Technology Letters. 19:774-776
Thin-film light-emitting diodes (LEDs) belong to the most successful LED concepts for achieving high efficiencies. The incorporation of buried microreflectors with inclined facets prevents the light generation under the top contact and bondpad and of
Photonic crystal structure effect on the enhancement in the external quantum efficiency of a red LED
Publikováno v:
IEEE Photonics Technology Letters. 18:1876-1878
The enhancement in external quantum efficiency of a red light-emitting diode (LED) from photonic crystal (PhC) hole patterns was investigated. A red LED was chosen because its epitaxial layers are relatively free from defects as compared to GaN-based
Autor:
Wolfgang Schmid, Marc Ilegems, Arndt Jaeger, R. P. Stanley, R. Joray, K. Streubel, Ralph Wirth, Rainer Butendeich
Publikováno v:
IEEE Photonics Technology Letters. 18:1052-1054
AlGaInP thin-film resonant cavity light-emitting diodes (RCLEDs) show an improved performance compared to standard red emitting RCLEDs. External quantum efficiencies at 650 nm of 23% and 18% with and without encapsulation, respectively, have been obt
Autor:
Ralph Wirth, Dominik Eisert, Madis Raukas, Frank Jermann, A. Linkov, Matthew A. Stough, M. Hannah, Nathan M Zink, Krister Bergenek, George C. Wei, John F. Kelso, Yi Zheng
Publikováno v:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XV.
Many LED-based applications would benefit from more efficient and/or high lumen output devices that enable usage in both white and single color illumination schemes. In the present article we briefly review the materials research history leading to o
Publikováno v:
IEEE Photonics Technology Letters. 13:421-423
We fabricated resonant-cavity light-emitting diodes (LEDs) emitting at 650 nm. Compressively strained GaInP quantum wells were used as an active layer embedded between AlGaAs-AlAs Bragg mirrors. The Bragg mirrors formed a one-wavelength optical reson