Design of an LED spot light system with a projection distance of 10 km

Chi Shou Wu, Kuan Yu Chen, Xuan Hao Lee, Shih Kang Lin, Ching Cherng Sun, Jhih You Cai, Tsung Hsun Yang, Yeh Wei Yu

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We designed a spot light system with an illumination range of 10 km. In the designed system, an appropriate white light-emitting diode (LED) was selected according to the exitance and injection power required. Subsequently, through a first-order optical design, the geometry of the lens and reflector was determined using geometrical calculation. Because the central illuminance of the projection spot of the reflector was 2.5 times that of the cover lens, we first considered the fabrication error of the reflector. According to the adjustment of the optimized distance between the white LED and reflector, we modified the design of the cover lens to fit the new location of the white LED. An LED spot light module containing 16 spot light units was used. The module’s power injection was only 68.2 W. Because of the excellent performance of the designed system in terms of the divergence angle of the projection beam and maximum luminous intensity, which were 1.6 and 2,840,000 cd, respectively, the projection distance of the LED spot light module was 3.37 Km, according to the ANSI regulation. Finally, a spot light system with nine modules and capable of achieving a projection distance of 10 km was successfully fabricated.

Original languageEnglish
Article number524
Issue number10
StatePublished - Oct 2019


  • Exitance
  • Long-distance projection
  • Spot light
  • White LED


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