In general, convex lenses, reflectors, Fresnel lenses, and a combination of lens-reflector in the light beam-collimating system are used for floodlights, aviation obstruction lights, and lighthouse beacons. Depending on which mode is used, there are some differences in the utilization of the beam, the rate of collimating, and the resolution of the heat release problem.
According to the present study, in the cylindrical Fresnel lens used in the optical system of aviation obstruction lights, the beams going beyond the height of the Fresnel lens from the light source in the center of the cylindrical lens are not used in the collimating system, which leads to the reduction in the overall optical efficiency and shortening of the lifetime of the light source, especially in the case of high-power LEDs, due to cooling.
Ho Ji Song, a researcher at the Faculty of Electronics, has proposed a method to design a new structure of lenses that can solve the problems of light beam utilization, collimating rate, and heat release by means of a total reflection-refraction coupling.
First, he made a combination of six submodels to construct a collimating lens that can collimate light from a single LED and multiple LEDs arranged side by side on one axis in the direction of the optical axis.
Second, in order to form a whole structure, he established the relationship between the structure parameters and positions during the optimization simulation of collimating LED light into the optical axis as it is also possible for the submodels to separate from each other by changing the structure parameters.
Finally, he determined the structure parameters of optimized collimating lens using the optimization function of LightTools, an optical simulation tool.
In order to verify the effectiveness of the new method, he performed a measurement test of light intensity and divergence angle on the designed lens, and introduced a new lens into the optical system of the medium intensity aviation obstacle light.
As a result, he drew the following conclusions.
First, the paraxial lights in the light beam from the LED is collimated in parallel with the optical axis through the central part of the lens and the other lights are collimated through the TIR surface, so that the utilization of the light beam as well as the rate of collimating can be increased.
Second, the proposed method can easily increase the light intensity by layering the lenses in the lamp design, and it can realize the dispersion of the LEDs, which is effective to solve the heat release problems in the high-power lamp design.
Third, the light from a single LED can be collimated vertically and horizontally and the light from the LEDs arranged side by side on one axis can be collimated vertically.
Fourth, the proposed method can be widely used to design lenses used in optical systems that need to cast light far away, such as floodlights, aviation obstacle beacons and lighthouse beacons.
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