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Proceedings Paper

Freeform étendue-preserving optics for light and color mixing
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Paper Abstract

Today’s SSL illumination market shows a clear trend towards high flux packages with higher efficiency and higher CRI, realized by means of multiple color chips and phosphors. Such light sources require the optics to provide both near- and far-field color mixing. This design problem is particularly challenging for collimated luminaries, since traditional diffusers cannot be employed without enlarging the exit aperture and reducing brightness (so increasing étendue). Furthermore, diffusers compromise the light output ratio (efficiency) of the lamps to which they are applied. A solution, based on Köhler integration, consisting of a spherical cap comprising spherical microlenses on both its interior and exterior sides was presented in 2012. When placed on top of an inhomogeneous multichip Lambertian LED, this so-called Shell-Mixer creates a homogeneous (both spatially and angularly) virtual source, also Lambertian, where the images of the chips merge. The virtual source is located at the same position with essentially the same size of the original source. The diameter of this optics was 3 times that of the chip-array footprint. In this work, we present a new version of the Shell-Mixer, based on the Edge Ray Principle, where neither the overall shape of the cap nor the surfaces of the lenses are constrained to spheres or rotational Cartesian ovals. This new Shell- Mixer is freeform, only twice as large as the original chip-array and equals the original model in terms of brightness, color uniformity and efficiency.

Paper Details

Date Published: 23 September 2015
PDF: 12 pages
Proc. SPIE 9629, Optical Systems Design 2015: Illumination Optics IV, 962905 (23 September 2015); doi: 10.1117/12.2191048
Show Author Affiliations
Simone Sorgato, Light Prescriptions Innovators Europe, S. L. (Spain)
Vrije Univ. Brussel (Belgium)
Rubén Mohedano, Light Prescriptions Innovators Europe, S. L. (Spain)
Julio Chaves, Light Prescriptions Innovators Europe, S. L. (Spain)
Aleksandra Cvetkovic, Light Prescriptions Innovators Europe, S. L. (Spain)
Maikel Hernández, Light Prescriptions Innovators Europe, S. L. (Spain)
Pablo Benítez, Light Prescriptions Innovators LLC (United States)
Univ. Politécnica de Madrid (Spain)
Juan C. Miñano, Light Prescriptions Innovators LLC (United States)
Univ. Politécnica de Madrid (Spain)
Hugo Thienpont, Vrije Univ. Brussel (Belgium)
Fabian Duerr, Vrije Univ. Brussel (Belgium)


Published in SPIE Proceedings Vol. 9629:
Optical Systems Design 2015: Illumination Optics IV
Tina E. Kidger; Stuart David, Editor(s)

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