Patent ID: 8466953

Claim:
An apparatus, comprising: a substrate of optical material having a first surface and a second surface, said substrate comprising a first area and a second area substantially adjacent to each other along a line; two diffractive elements disposed on the first or the second surface and configured to receive sequentially two input optical beams comprising an optical image of a display such that one of the two input optical beams is received by one of the two diffractive elements and another of the two input optical beams is received by another of the two diffractive elements, wherein one of the two diffractive elements is disposed on the first area and another of the two diffractive elements is disposed on the second area, respectively, wherein said two diffractive elements are substantially next to each other and adjacent to said line; two further diffractive elements disposed on the first or the second surface, wherein one of the two further diffractive elements is disposed on the first area and another of said two further diffractive elements is disposed on the second area, respectively; and an optical delivery system, configured to sequentially switch said two input optical beams comprising the optical image of the display between said two diffractive elements; and wherein the apparatus is configured such that: at least part of each of the two sequentially switched input optical beams at any time is diffracted only in one of the two diffractive elements to provide a diffracted optical beam in the same area with said one of the two diffractive elements substantially within the first and second surfaces, and at least part of the diffracted optical beam in the first or the second area is further coupled out of the substrate by diffraction in one of said two further diffractive elements for providing two sequentially switched output optical beams, each comprising the optical image of the display with an expanded exit pupil in one or two dimensions.