Formation of multiple aerial LED signs in multiple lanes formed with AIRR by use of two beam splitters

Abstract

We propose multiple aerial imaging system by use of two beam splitters in the optical system of aerial imaging by retro-reflection (AIRR). The AIRR optical system consists of a light source, a beam splitter, and a retro-reflector. Use of two-layered beam splitters enables us to show multiple aerial signs to drivers in multiple driving lanes. The purpose of this paper is to confirm feasibility that an aerial display by use of AIRR for a novel traffic information provision. First, we explain an optical configuration to show aerial images to multiple road lanes, a driving lane and an overtaking lane with AIRR by use of two beam splitters. Next, we have developed a prototype optical system by use of two large beam splitters and a large high-brightness LED sign that is designed to be used for actual road displays. The light source was an LED display with a height of 450 mm and a width of 390 mm, which shows a character. We observed aerial images by naked eyes as experiments. And we discuss the issues for practical application that the experiments have revealed.