Abstract: A planar substrate having a first diffractive element for coupling light waves of different colors into the substrate and guiding the light waves by successive internal reflections. A second diffractive element, disposed on the substrate, causes the guided light waves to be partially transmitted out of the substrate where the light waves encounter the second diffractive element. Because light waves of each color are reflected at different reflection angles, the light waves with smaller reflection angles encounter the second diffractive element at more locations than those with larger reflection angles, resulting in color non-uniformity in the light transmitted out from the substrate surface. One or more interfaces are provided between the surfaces of the substrate to selectively reflect the light waves having larger reflection angles toward the second diffraction element, so that light waves of different colors encounter the second diffraction element substantially at the same number of locations.

Abstract: A method and system for providing comfort noise in the non-speech periods in speech communication. The comfort noise is generated based on whether the background noise in the speech input is stationary or non-stationary. If the background noise is non-stationary, a random component is inserted in the comfort noise using a dithering process. If the background noise is stationary, the dithering process is not used.

Abstract: An optical hinge and an optical hinge apparatus for providing an optical link between a first circuit board and a second circuit board. The optical hinge is made of two optical components, separated by an air gap, to allow a light beam to transmit from one optical component to another via the air gap. The optical components can be rotated relative to each other along a rotation axis. Each of the optical components is optically coupled to an opto-electronic device on a circuit board. Preferably, the light beam is transmitted through the air gap along an optical path which is substantially parallel to or coincident with the rotation axis. The light beam can be used to carry optical signals in order to convey communication data from one circuit board to another. The optical signals can be transmitted in infrared frequencies or visible frequencies.

Abstract: A method and apparatus for making insignias with a raised design is capable of providing more aesthetic appearance to the insignias thus made. A base material consisting of a base sheet and a surface sheet overlaying the base sheet is prepared for making into an insignia. The base material is coating with a surface coating of decorative material. A bottom mold and an upper mold are used to press the base material to form raised design of patterns. The bottom and upper molds are coupled to a composite heating device including high-frequency induction and electric heating means for applying both high-frequency induction heat and electric heat to the base material while the upper molding is being pressed against the bottom mold. The upper mold is formed with a plurality of edge-defining blades for cutting an edge for the insignia, a plurality of pattern-defining blades for forming a pre-designed pattern on the insignia.