Enhancement and directional control of light output of scintillators by using microlens arrays: A numerical simulation study

In this investigation, we have carried out the simulations of light output and the directionality of emission from scintillators coated with microlens arrays by using the ray-optics method. We systematically analyze the impact of an individual microlens at different positions on the light output intensity and the directional control, followed by an entire understanding of microlens arrays. It is found that microlens arrays can be used to increase the extraction efficiency and control the directionality of emission of scintillation light. The multiple reflections by the lateral and bottom surfaces play an important role. A comprehensive understanding of the impact of the ratio of width and thickness of a scintillator and the refractive index of microlens is presented and discussed in details. The maximum angle-integrated intensity could be obtained when the refractive index of microlens is slightly larger than that of scintillator. Simulations based on genetic algorithms can be used to efficiently design the parameters of microlens arrays with a specific target of a combination of emission angle and total emission intensity.