Challenges and improvements in LED-pumped luminescent concentrators

Christoph Hoelen; Dominique Bruls; Wilco Keur; Dany Benoy; Jannie Baken; Ivo Durlinger; Jan Jansen; Ludo Haenen; Barry Mos; Joan Yu; Simon Kadijk; Eric van Grunsven

doi:10.1117/12.2543734

25 February 2020 Challenges and improvements in LED-pumped luminescent concentrators

Christoph Hoelen, Dominique Bruls, Wilco Keur, Dany Benoy, Jannie Baken, Ivo Durlinger, Jan Jansen, Ludo Haenen, Barry Mos, Joan Yu, Simon Kadijk, Eric van Grunsven

Author Affiliations +

Proceedings Volume 11302, Light-Emitting Devices, Materials, and Applications XXIV; 113020A (2020) https://doi.org/10.1117/12.2543734
Event: SPIE OPTO, 2020, San Francisco, California, United States

Abstract

As the brightness of high-power LEDs is generally limited to less than ca 200 Mnit (200 x 10⁸ lm/m²sr), and expectations are that this will stay limited to a few hundred Mnit for optimized devices, high luminance light modules have been developed during the past few years based on luminescent concentrators. With these light sources the requirements can be met for most high luminous flux applications with limited étendue, like in stage and entertainment lighting or in digital projection, where LEDs don’t meet the specifications. In this paper we report on the challenges of High Lumen Density (HLD) light engine concepts based on transparent luminescent concentrators pumped by blue LEDs and on the large improvements that were recently made with respect to luminance and module efficacy while significantly simplifying the architecture. For mainstream LCD-based front projection systems, typically a yellow-green light source with an étendue of less than 14 mm²sr and a luminous flux of more than 14 klm (DC) is requested to enable > 4k ANSI-lm while meeting a high-quality color gamut. By optimizing the pump LEDs and the light coupling configuration and by decoupling the thermal channels for converter and pump LEDs in a simplified module architecture, we have improved the efficacy from 55 lm/W to more than 70 lm/W for 15 klm yellow-green output with a luminance well over 1 Gnit while reducing the module complexity considerably. With the same concept a DC luminous flux of 19 klm was achieved within an étendue of 13.6 mm²sr (i.e., 1.4 Gnit). By design, the preferred trade-offs can be made between efficiency, luminance, luminous flux, module size, and cost. Thanks to this new architecture, further optimization for the specific applications is possible, enabling also more temperature-sensitive converter materials to be applied successfully.

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Christoph Hoelen, Dominique Bruls, Wilco Keur, Dany Benoy, Jannie Baken, Ivo Durlinger, Jan Jansen, Ludo Haenen, Barry Mos, Joan Yu, Simon Kadijk, and Eric van Grunsven "Challenges and improvements in LED-pumped luminescent concentrators", Proc. SPIE 11302, Light-Emitting Devices, Materials, and Applications XXIV, 113020A (25 February 2020); https://doi.org/10.1117/12.2543734

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