Design of a high-efficiency narrow spot headlamp with distributed LEDs

In this talk, we present a narrow spot headlamp system of the dual half circular parabolic aluminized refl ector (PAR). This system has a property that each of the half-circular PAR contains fi ve high-effi ciency and small package light emitting diode (LED) chips with 180o rotational symmetry. Concerning traffic safety, the design criterion of train headlamp is to meet the code of Federal Regulations (CFR). In terms of the forecast of illuminated position on a screen, analytic derivation has been developed to study the optical path of a ray which is perpendicular to and emitted from the center of the LED chip. This ray stands for the main emitted ray of the LED chip and it is inside of the illuminated spot by the LED source on the screen. Therefore, we can analyze design systematically for determining where the LED chips ought to be placed in the PAR reflector for minimizing electricity consumption while satisfying the reliability constraints on train headlamp to ensure traffic safety. Compared to a typical train headlamp system with incandescent or halogen lamp needing several hundred watts, the proposed system only uses 20