Proposal of moire-free aerial display based on the LED panel and apertured retro-reflector

We have realized a novel optical system to form a large aerial image in front of a full-color LED panel that is covered with retro-reflector. The retro-reflector has square apertures through which lights from the LED pixels pass. Our optical system is based on aerial imaging by retro-reflection (AIRR). The aerial image formed with AIRR is visible over a wide viewing angle without using 3D glasses. To reduce the system volume, a beam splitter is placed parallelly in front of the LED panel covered with the retro-reflector. Because the apertured retro-reflector is placed on the LED panel, no moiré occurs between the apertures in the retro-reflector and black regions on the LED panel. We have analytically clarified the optimal aperture ratio in the proposed optical system to increase the luminance of the aerial image. Furthermore, we have developed a prototype for experimental confirmation of our optical system and measured of the luminance intensity of the aerial images. Consequently, we have confirmed measured results are consistent with our analysis. Showing aerial signage in front of an LED panel reduces the foot space, which is suitable for the installation of a large-scale aerial display for advertisement and exhibitions.