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Optical Engineering

Simultaneous multiple surface design of compact air-gap collimators for light-emitting diodes
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Paper Abstract

The simultaneous multiple surface (SMS) method is used to design air-gap RXI-type lenses, which efficiently produce a very narrow beam from high-powered LEDs. These designs are compact, with both front surface and reflecting back surface calculated simultaneously from periphery inward, as profiles of circular symmetry, via applying the edge-ray principle to the chip geometry. The light source is a Lambertian-glowing cube 1.2 mm square and 0.15 mm high, as viewed through its clear (n = 1.54) package dome, with emission down to 95 deg from the symmetry axis. A given exit-aperture diameter defines a minimum, étendue-limited collimation angle, α = arc sin (chip-width/diameter). At the center of the back surface there is a cavity surrounding the source. The front surface reflects that source flux to the back surface, which reflects it back forward again, accomplishing the optical folding thereby. The back surface is shaped so that the light it reflects forward will be refracted out the front surface to become the collimated output beam.

Paper Details

Date Published: 1 July 2004
PDF: 9 pages
Opt. Eng. 43(7) doi: 10.1117/1.1753588
Published in: Optical Engineering Volume 43, Issue 7
Show Author Affiliations
Fernando Munoz, Univ. Politecnica de Madrid (Spain)
Pablo Gimenez-Benitez, Univ. Politécnica de Madrid (Spain)
Oliver Dross, Light Prescriptions Innovators Europe (Spain)
Juan Carlos Miñano, Univ. Politécnica de Madrid (Spain)
William A. Parkyn, Light Prescriptions Innovators (United States)


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