Harnessing and cloaking optical boundary in lens-array based display

Abstract

Optical boundaries are basic structures for optical system and they become visible where reflection and refraction occur. The visible boundary is very often presented as a nuisance to optical systems in imaging recording or in display. Harnessing the optical boundaries up to a complete carpeting is scientifically interesting and technologically important. This work describes the concept, design, fabrication and testing of novel Fresnel lens array with tailored microstructures to carpet the optical boundaries while the functionality such as focusing and deflection can be retained. A gradually interleaved and periodically arranged micro-structured Fresnel lens sheet acting as low band pass filter lens array is proposed, fabricated and tested. The novel Fresnel lens array is demonstrated to remain the optical features for perfect planar display. When it is applied to a backlight illuminated display system, tailored illumination with local dimming further helps improving the visual homogeneity. The combined use of these new techniques allows the boundary cloaked completely over a large viewing directional range for broad visible spectra. The cloaking technique is applied as an immediate example to an autostereoscopic display system and is shown to be practical and valid for imaging and display optics.