OSA's Digital Library

Energy Express

Energy Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. S6 — Nov. 7, 2011
  • pp: A1190–A1195

Reliability of point source approximations in compact LED lens designs

Thøger Kari, Jesper Gadegaard, Thomas Søndergaard, Thomas Garm Pedersen, and Kjeld Pedersen  »View Author Affiliations

Optics Express, Vol. 19, Issue S6, pp. A1190-A1195 (2011)

View Full Text Article

Enhanced HTML    Acrobat PDF (977 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



In many applications, compact concentrator lenses are used for collimating light from LEDs into high output beams. When optimizing lens designs, the LED is often approximated as a point source. At small lens-to-LED size ratios this is known to be inaccurate, but the performance compared to optimizations with more realistic models is rarely addressed. This paper examines the reliability of a point source model in compact lens design by comparing with optimisations that use a factory measured LED ray-file. The point source is shown to cause significant, unnecessary efficiency loss even at large lens sizes, while the use of a ray-file allows for a >55% reduction in the footprint area of the lens. The use of point source approximations in compact lens designs is therefore generally discouraged.

© 2011 OSA

OCIS Codes
(000.4430) General : Numerical approximation and analysis
(220.2740) Optical design and fabrication : Geometric optical design
(230.3670) Optical devices : Light-emitting diodes
(220.4298) Optical design and fabrication : Nonimaging optics

ToC Category:
Light-Emitting Diodes

Original Manuscript: August 22, 2011
Revised Manuscript: September 14, 2011
Manuscript Accepted: September 14, 2011
Published: September 23, 2011

Thøger Kari, Jesper Gadegaard, Thomas Søndergaard, Thomas Garm Pedersen, and Kjeld Pedersen, "Reliability of point source approximations in compact LED lens designs," Opt. Express 19, A1190-A1195 (2011)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. J. Jiang, S. To, W. B. Lee, and B. Cheung, “Optical design of a freeform TIR lens for LED streetlight,” Optik (Jena)121, 1761–1765 (2010).
  2. A. Domhardt, U. Rohlfing, S. Weingaertner, K. Klinger, D. Kooß, K. Manz, and U. Lemmer, “New design tools for LED headlamps,” Proc. SPIE7003, 70032C, 70032C-10 (2008). [CrossRef]
  3. A. Domhardt, S. Weingaertner, U. Rohlfing, and U. Lemmer, “TIR Optics for non-rotationally symmetric illumination design,” Proc. SPIE7103, 710304 (2008). [CrossRef]
  4. T. Kari, J. Gadegaard, D. T. Jørgensen, T. Søndergaard, T. G. Pedersen, and K. Pedersen, “Compact lens with circular spot profile for square die LEDs in multi-LED projectors,” Appl. Opt.50(24), 4860–4867 (2011). [CrossRef] [PubMed]
  5. K. Wang, F. Chen, Z.-Y. Liu, X.-B. Luo, and S. Liu, “Design of compact freeform lens for application specific Light-Emitting Diode packaging,” Opt. Express18(2), 413–425 (2010). [CrossRef] [PubMed]
  6. J.-J. Chen and C.-T. Lin, “Freeform surface design for a light-emitting diode-based collimating lens,” Opt. Eng.49(9), 093001 (2010). [CrossRef]
  7. H. Ries and J. Muschaweck, “Tailored freeform optical surfaces,” J. Opt. Soc. Am. A19(3), 590–595 (2002). [CrossRef] [PubMed]
  8. P. Benítez, J. C. Miňano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng.43(7), 1489–1502 (2004). [CrossRef]
  9. CBT-90 series LEDs, Luminus Devices, Inc., http://www.luminus.com .
  10. N. Shatz and J. C. Bortz, “Consequence of symmetry” in Nonimaging Optics, R. Winston, J. C. Miňano, and P. Benítes, (Elsevier, 2005), pp. 235–264.

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


Fig. 1 Fig. 2 Fig. 3
Fig. 4 Fig. 5

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited