| 摘要 |
<p>The specification and drawings present a new method, apparatus and software product for illuminating different graphical layouts in a component comprising an optical device, e.g., in a keyboard or in a liquid crystal display of an electronic device. The optical device uses a diffractive planar waveguide comprising diffraction gratings disposed on a lightguiding plate and the property that a short period diffractive grating has no diffraction orders at certain conical angles. Therefore, the outcoupling gratings on the waveguide are designed so that the optical beam coming from a certain direction can be effectively coupled out of the waveguide or be kept confined inside of the waveguide due to a total internal reflection. Then different graphical layouts can be disposed on the waveguide using, e.g., pixels having diffraction gratings with periodic lines at different orientations.</p> |
