A thorough investigation into the efficiency and performance of off-axis, freeform illumination systems has been conducted, and a method for arriving at the optimal tilt is established for both reflective and refractive designs. The optimal tilt for refractive designs is determined by minimizing the total light lost due to Fresnel reflections across the lens, while the optimal tilt for reflective designs ensures the source is not obstructing the reflected ray bundle. For uncoated lenses, utilizing the proposed tilt can improve efficiency by more than 150%.
- illumination design
- nonimaging optics
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics