Combining the transformation and the integration methods to design a refractive lens-array for signal lighting applications

Abstract

The design of a secondary optical lens for light beam shaping using the transformation method is performed by transforming the light source energy distribution using the concepts of energy conservation and light energy mapping. Using these concepts creates a dependency relation between the output optical performance and the luminous intensity distribution of the light source. This relation leads to errors on the optical performance due to the fabrication misalignment between the light source and the secondary optical lens. On the other hand, in the illumination applications, the integration method has been proved to be an efficient method for achieving a high degree of homogenized luminous intensity distribution by integrating and superimposing the light source energy over the illuminated objects. In signal lighting applications, the luminous intensity distribution must meet the requirements regarding the brightness perception of users over the spatial angular distribution, not the illumination of objects. In this paper, the integration method is combined with the transformation method to design a refractive lens-array for signal lighting applications. The difference between the two methods is described, presenting the advantages of the combination process. Design procedures are explained in detail including the lens-array modeling. The optical performance is investigated using an optical ray tracing. Finally, the influence of the misalignment between the light source and the refractive lens-array is measured.