Use Freeform Reflector Method In Lighting Coupler

The Natural Light Guiding System(NLIS (R)) developed at NTUST is designed to guild the outdoor sunshine for indoors illumination. The system can be divided into three subsystems: the light collecting sub-system(LCS), the light transmitting sub-system(LTS), and the light emitting subsystem(LES). These three sub-systems are intimately connected with one another. However, a great deal of energy is wasted during the process of passing the sunlight from the LCS to the LCS. In this research, we design an optical coupler based on a combination of "The Power Index of Energy" and "Free-form" structure to improve the efficiency. Six time periods were selected when the sunlight was the strongest during a day. Six different angles were produced by these six rays of the sunlight. And the six angles of incidence could be derived from the "Equation of Internal Circle." Using this method accompanying with the "Discrete surface" built by "The Power Index of Energy," the "Reflect surface" was formed. Through the stimulations and analyses of this "Reflect surface" by the optical software, the results showed that the efficiency of the light transmission was improved more than three times comparing to the original system.