Mitsubishi Electric has developed an 'aerial display' that projects images (measuring 56in diagonally) into mid-air.
The display has a wide range of potential applications, and Mitsubishi Electric says the technology will be commercially available from 2020 onwards for applications in digital signage, entertainment and other sectors.
The two key components for the new technology are a beam splitter - an optical device that divides incoming light into reflected light and transmitted light - and a retro-reflective sheet - an optical device that reflects incoming light back in the incident direction. A beam splitter and retro-reflective sheet are arranged in a set with a screen.
The light that is projected from the screen is reflected by the beam splitter and then subsequently by the retro-reflective sheet. The result is that the light reconverges as an image that appears to be floating in the air (Figure 2 below).
To realise this technology, Mitsubishi Electric developed an optical simulation program to calculate the optimal arrangement of the screen, beam splitter and retro-reflective sheet to achieve an aerial display measuring approximately 56in diagonally (886mm x 1,120mm) projected at least one metre from the beam splitter.
One problem was that people who are not accustomed to focusing their eyes on open space find it difficult to understand where an aerial image is being displayed without physical cues. To address this, Mitsubishi Electric developed a system that uses a projector to display guide images on the walls on both sides of the aerial image to indicate the position.
This system divides an input into left and right guide images and the aerial image, but links the three seamlessly for high entertainment value. Factoring in the size of the guide images, the total display area measures approximately 90 inches diagonally (1,992mm wide and 1,120mm high).