Optical Review

, Volume 16, Issue 3, pp 318–322

New collection systems for multi LED light engines

  • Sheng-Han Tu
  • Jui-Wen Pan
  • Chih-Ming Wang
  • Yeeu-Chang Lee
  • Jenq-Yang Chang
Regular Papers


Light emitting diodes (LEDs) have numerous advantages as light sources in projectors. LEDs are more compact, exhibit a larger color gamut, have a longer lifetime, and need a lower supply voltage. However, there is still one important disadvantage: the optical power per unit of étendue (luminance) of an LED is significantly low. As a result of the étendue limitations of LEDs, the projected flux on the screen will not be high. Despite this shortcoming, LED’s are still of great interest for low power applications because of their other superior properties. Thus we collect the available light flux optimally and combine multiple high luminance LEDs within the system. In this study we discuss three collection systems designed to collect the LED flux with high optical efficiency while retaining small device size. The best collection efficiency attained with our collection systems is 96%. The fabrication tolerance and cost of our collection systems are also analyzed.


pocket size projector collection system light emitting diode (LED) light source light engine collection system 


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Copyright information

© The Optical Society of Japan 2009

Authors and Affiliations

  • Sheng-Han Tu
    • 1
  • Jui-Wen Pan
    • 1
  • Chih-Ming Wang
    • 2
  • Yeeu-Chang Lee
    • 3
  • Jenq-Yang Chang
    • 1
  1. 1.Department of Optics and PhotonicsNational Central UniversityJhongliTaiwan, R.O.C.
  2. 2.Institute of Opto-Electronic EngineeringNational Dong Hwa UniversityHualienTaiwan, R.O.C.
  3. 3.Department of Mechanical EngineeringChung Yuan Christian UniversityJhongliTaiwan, R.O.C.

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