Proc. SPIE. 9672, AOPC 2015: Advanced Display Technology; and Micro/Nano Optical Imaging Technologies and Applications
KEYWORDS: Optical design, Light sources, Light emitting diodes, LED lighting, Detection and tracking algorithms, Lens design, Monte Carlo methods, Ray tracing, Light sources and illumination, Near field optics
As the low luminous flux of one single LED, LED chip array plays important effect on achieving high luminous flux in all kinds of applied field, such as automotive lighting, street lighting, sensing and imaging, etc. However, LED chip array is an extended source rather than a point source of conventional one single LED. Obviously, lens design for LED chip array will be reconsider and redesign to accommodate this difference. In recent years, as the development of illumination optics, some excellent optical design methods for extended source have been improved and suggested. When the design method for point source is adopt to design the LED chip array with high flux and high uniformity, the obtained Lens is so huge that the advantage of small LED chip is dissipated at this condition. The supporting surface method is effective and commonly used. However, it is not convergent when solving the refractor problem of designing point light source near field. Based on the property of Cartesian oval, a modified method is proposed and the convergence of the modified method is verified by Monte-Carlo ray trace. The number of the Cartesian oval and the size of the lens can be firmly under control during the design, while generally the ratio between the sizes of the lens and the chip is greater than 5. Based on the modified supporting surface method, a compact lens design method for extended light source is constructed. And the LED illumination lens is designed by this method and fabricated, and the simulation result shows that this LED illumination lens can achieve uniform illumination at target surface.
With high light efficiency and long aging life, LED solid-state light source has attracted much attention in underwater application, such as optical communication and imaging. But, the large divergence angle of LED illumination has been a big challenge in practical underwater application, such as the light attenuation in water and then the decreased signal-to-noise ratio. Source-target map is a vital method in illumination optics design, and the focus is to solve numerically differential equations and then construct the freeform surface. To achieve high accuracy freeform surface, an improved method is suggested and optimized through much more advanced and accuracy Runge-Kutta method, which is different from the original design one through Euler method. The designed lens is simulated by ray trace software TracePro, and the simulation results show that the uniformity of 0.8 and the efficacy of 0.6 is obtained. While as, the method is proven to be effective, and also the accuracy of the smooth freeform surface is strengthened. One designed illumination lens is fabricated by computer numeric control (CNC) machine to demonstrate the design experimentally.