US Patent 11829010 Optical waveguide

An optical waveguide, including a first structural layer, a second structural layer, a first light-guiding element, and multiple second light-guiding elements, is provided. The light-guiding elements are a partially penetrating and partially reflective layer. Multiple first sub-beams in an image beam are transmitted in the first or the second structural layer by a coupling inclined surface. Each first sub-beam forms multiple second sub-beams after being transmitted by the first or the second light-guiding elements. Some of the second sub-beams are coupled out of the optical waveguide by the second light-guiding elements, thereby enabling the image beam to expand in a first direction. For a portion of the visible light waveband, a trend of transmittance of the partially penetrating and partially reflective layer changing as a wavelength increases is opposite to a trend of transmittance of the first structural layer or the second structural layer changing as the wavelength increases.