Mitsubishi’s ‘Aerial Display’ Projects Large Images in Mid-air

By Tom Allen
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At its annual R&D Open House event in Japan, Mitsubishi presented an ‘aerial display’ that is able to project images measuring up to 56″ diagonally in mid-air.

Mitsubishi describes the two key components of the technology as a beam splitter and a retro-reflective sheet. The former divides incoming light into reflected and transmitted light; the latter reflects incoming light back into the incident direction. Both are arranged in a set with a screen. Light projected from the screen is reflected by the beam splitter and then again by the retro-reflective sheet. The light reconverges as a an image that appears to be floating in the air.

An optical simulation program was developed to calculate the optimal arrangement of the screen, splitter and sheet to achieve the aerial display, projected at least 1m from the beam splitter.

It was found that people, who are not accustomed to focusing their eyes on open space, find it difficult to understand where the display is being projected without any physical cues. Mitsubishi solved this using a projector to display guide images on the walls on both sides of the aerial image; this indicates the position. An input is divided into left and right guide images and the aerial image; the three are ‘seamlessly’ linked.