Watching TV or digital videos wherever we are is now possible with the array of portable media players on the market, but somehow the viewing experience on such a small screen is still not that satisfying. Those who opt for video glasses will be able to enjoy a big screen experience, but they will have to stay put where they are since they’ll be essentially blind to the outside world. The Lumus PD-20 changes that as it displays video by reflecting images directly in the eye’s line of sight from the box which is attached to the frame as seen on the right. This means you’ll be able to enjoy your favorite movies anytime, anywhere while retaining the ability to see where you’re going thanks to the transparent display panel.
The LOE
Lumus’ patented, revolutionary Light-guide Optical Element (LOE) comprises a flat, transparent optical substrate that incorporates a set of embedded partially reflecting facets. The upper figure illustrates the LOE function. An optical image, generated by a microdisplay (e.g. LCD, LCoS or OLED), is coupled into the LOE substrate. Trapped by total internal reflection, the image components are guided along the LOE. The image is then expanded and coupled out by a set of partial reflectors for viewing by the user. The LOE provides the viewing experience of a large distant screen: an enlarged, distant image, with a large field-of-view (FoV).
LOE Features
The LOE is thin and, as it expands, the optical exit pupil can work with a small image source. Consequently, the LOE offers unprecedented compactness, breaking the conventional tradeoff between the optical performance and the physical size of a near-to-eye display. Unlike conventional optics, the FoV, eye motion box (the volume in which the eye should be located to view the entire image) and overall size of the optical system are all independent of the LOE thickness. For example, the thickness of conventional imaging optics increases dramatically with FoV (graph on right). In contrast, a 2-3mm thick LOE supports even very large FoVs. In addition the LOE is free of chromatic aberrations and optical distortions, delivering a high-resolution quality image.
