Ultra-slim, mid-air display based on planar DOE waveguide

Mid-air display (MAD) technology is attractive to practitioners nowadays. The interest is due to the potential application in consumer products with embedded floating image displays, like smartphones, smartwatches and dock-stations, and as a part of new holographic user interfaces for safe and contactless control. Some of the problems to solve on the way to compact and light efficient MAD include small field of view, small image size, low image resolution, low image contrast, absence of image magnification, low perceived sense of depth, etc. In order to overcome these challenges, the authors propose a MAD based on a DMD pico-projector and a DOE waveguide with a positive Fresnel lens, placed near the outcoupling aperture of the DOE waveguide. The developed MAD forms a real image with a positive relief from the display surface so that the viewer perceives this image floating in front of it, at the back focal plane of the Fresnel lens. For midair image with >= 1-inch diagonal with 57 mm image relief horizontal field of view was 35 degrees, with image brightness 100 cd/m(2). The proposed mid-air image display has a compact form factor with dimensions 100 mm x 50 mm x 3 mm, without dimensions of the DMD pico-projector. It can be used in consumer products to provide a new kind of experience including contactless holographic user interaction.