Design of efficient lightpipes for illumination by an analytical approach

We present the concept of principal sections of a lightpipe to analyze the propagation of light through the lightpipe by total internal reflection. Only the principal sections determine the acceptance angle and thus help in the identification of regions where the leakage occurs first. Use of principal sections for analysis leads to a significant reduction in the design effort. We present an analysis of several commonly used lightpipe configurations, e.g., straight and single circular bend, and different cross sections, e.g., elliptical and rectangular. This analysis leads to the maximization of throughput and transfer efficiency. The uniformity characteristics of elementary configurations and scaling factors for a lightpipe with a single circular bend are also discussed.