A multi-directional backlight for a wide-angle, glasses-free three-dimensional display

A multiview, dynamic three-dimensional display suitable for mobile devices is achieved by using a set of directional grating pixels etched on the backlight surface; such glasses-free displays could revolutionize areas such as data visualization, medical training and entertainment. 3D mobile displays Glasses-free three-dimensional (3D) displays could revolutionize areas such as data visualization, medical training and entertainment, particularly if adapted to mobile devices. Holography can provide ideal 3D viewing but is too slow or expensive for many applications. Multiview approaches are the alternative, exploiting various geometric optical tricks to create 3D images that can be viewed from many directions at the same time. A team working at Hewlett-Packard's laboratories in Palo Alto has developed a new multiview 3D display that is particularly well suited to mobile devices, which require thin displays with high spatial resolution and a wide-angle view zone. Central to the new device is a set of directional grating pixels, associated with different views and colours, etched on the backlight surface. The display uses an LED-lit backlight very similar to those in use in LCD screens today, and is demonstrated in action in transparent hand-held prototypes showing animated sequences of up to six different 200-view images at a resolution of 127 pixels per inch. Multiview three-dimensional (3D) displays can project the correct perspectives of a 3D image in many spatial directions simultaneously 1 , 2 , 3 , 4 . They provide a 3D stereoscopic experience to many viewers at the same time with full motion parallax and do not require special glasses or eye tracking. None of the leading multiview 3D solutions is particularly well suited to mobile devices (watches, mobile phones or tablets), which require the combination of a thin, portable form factor, a high spatial resolution and a wide full-parallax view zone (for short viewing distance from potentially steep angles). Here we introduce a multi-directional diffractive backlight technology that permits the rendering of high-resolution, full-parallax 3D images in a very wide view zone (up to 180 degrees in principle) at an observation distance of up to a metre. The key to our design is a guided-wave illumination technique based on light-emitting diodes that produces wide-angle multiview images in colour from a thin planar transparent lightguide. Pixels associated with different views or colours are spatially multiplex