Near-to-eye display based on retinal scanning and a diffractive exit-pupil expander

In this paper, we propose a novel design to construct a near-to-eye display with an appearance resembling that of a regular eye wear. Our design combines a scanning display engine with a diffractive exit pupil expander. Both of these components have been used separately earlier, but we propose to combine them in a single device. This allows the construction of a smaller and lighter display system, as well as a more power efficient design as compared to traditional micro display based systems. In our design the light source can be moved away from the display to decrease the weight and size. An exit-pupil expander based on diffractive optics allows a size and weight efficient way to build a near-to-eye display with a large exit pupil. A large exit pupil is desired in near-to-eye displays to accommodate the eye movements and to improve the comfort and ease of the use. The diffractive exit-pupil expander also allows a switchable see-through feature; enabling the viewer the see the surroundings together with the displayed information. In the paper the operation and the design of the proposed near-to-eye display are described. We also present modeling results that support the validity of the design, and finally some preliminary measurement results are given.