Freeform Secondary Optics for LED Independent Beam-shaping

Abstract

This research is conducted to solve a functional principle problem in light beam shaping in the field of illumination. Beam-shaping is the process of redistributing the light intensity to meet the application’s requirements using secondary optical systems (e.g., refractive lenses). The functional problem is the deviation of the created output light intensity distribution from the expected design objective, which is observed very often in the experimental setups. The output intensity deviations could be due to deviations in the input source intensity. Therefore, the focus is to develop a secondary lens design approach to perform beam-shaping. This design approach reduces the dependency relationship between the input source intensity distribution and the created output target intensity distribution. This thesis deals with modeling, designing, simulating, and testing several secondary lenses. The current state-of-the-art design approaches are overviewed, and practical examples are used to present the source-target dependency problem. Both analytical and numerical methods are discussed to perform light beam shaping in different levels of complexity. The main contribution of this thesis is the development and testing of a combined design approach for creating freeform lens-arrays (working almost independently of the light source intensity distribution). Results show the ability to perform light beam-shaping, almost independent of the light source intensity distribution. This could be achieved by combining two design approaches in designing freeform lens-arrays to redistribute and superimpose the light intensity. The source-target independence relationship leads to the ability to consider the input light source intensity as a uniform intensity distribution taking into account the number of freeform lens-lets. The independence relationship could be improved by increasing the number of the superimposed light distributions by increasing the number of freeform lens-lets. The increment of the freeform lens-lets should be performed considering the fabrication limits. The optical function of the designed freeform optics is evaluated numerically using the lab software ZEMAX-OpticStudio and experimentally using the lab testing setups. Finally, several application examples are investigated considering the combined design approach.