No-loss bent light pipe with an equiangular spiral

Abstract

Bending a light pipe and maintaining the required volume and size, while at the same time preserving source energy and minimizing bend losses, is the basic criterion for designing a light pipe. An important requirement is the design of a light pipe that is capable of being bent without loss of light and with no limitations on acceptance angle. It is shown that in theory such a light pipe does exist, in a form corresponding to the so-called golden rectangle. Numerical simulations with six different no-loss light pipes with multiple bends are provided as a demonstration.

Toleranced freeform optical design with extended sources using ray targeting

“…This shape ensures capture of the input light with the use of TIR. 13 Additionally, the lightpipe has a hexagonal cross section in order to break symmetry concerns and then has a slight flare to improve spatial uniformity at the output. 14 The design provides angular output over a polar angle of ±45° rather than the hemisphere from the nearly Lambertian output of the selected LED.…”

Design of circular-shape no-loss bent lightpipe with a novel transform of elliptical form

“…To move B ' to the position B, D 'will be shifted to the position D for this kind of connection in order to satisfy the required width of light pipe W. As that illustrated in Ref. [5], we could choose the inner curve to compliment the condition we mentioned to ensure the size of the entrance port is the same with the existence port.…”

“…[5] is rectangle which means we can only allow four kind of connection between two light pipes, i.e., (1) 0 degree, (2) In other words, the bending is a two-dimensional bending only.…”

“…How to reduce the bending loss even prevent the loss of leakage while bended in bent light pipes has been one of the important issues in this field. Recently, as illustrated in one paper [5]: No-loss bent light pipe with a shape related to the equiangular spiral cracks the crux of preventing the bending loss. Fig.…”

“…One can construct the model of such a bent light pipe by referring to Fig.2 similarly that shown in Ref. [5]. For a given width of the light pipe W, there is a value of C, we use C 0 , such that C 0 follows:…”