Optical Waveguide Wavelength Compensation for Color Uniformity
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Solution Overview
Problem
Optical waveguides made from polymer materials in near-eye displays suffer from color deviations due to varying transmittance and absorptivity with wavelength, leading to non-uniform image colors for the viewer.
Innovation Solution
An optical waveguide design featuring a first and second structural layer with a partially transmissive and reflective light-guiding element, where the transmittance trend with wavelength is opposite to that of the structural layers, ensuring balanced light absorptivity across wavelengths and improving color uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer material is used for optical waveguide, then manufacturing cost is reduced and fabrication is simplified, but color uniformity deteriorates due to wavelength-dependent transmittance and absorptivity
Solution Approach 1:
The patent uses a composite structure consisting of a polymer waveguide body with multiple light-guiding elements (gratings or prisms) formed on its surface. These light-guiding elements are designed with specific geometric parameters to compensate for the wavelength-dependent optical properties of the polymer material, achieving color uniformity while maintaining the manufacturing advantages of polymer materials.
Solution Approach 2:
The patent applies different local optical structures (light-guiding elements with varying geometries, periods, or orientations) at different positions or for different wavelength ranges within the waveguide. This local differentiation allows specific compensation for the wavelength-dependent transmittance and absorptivity of the polymer material in different regions, thereby achieving overall color uniformity across the entire image.
2Ease of manufacture
If polymer material is used for optical waveguide, then manufacturing cost is reduced, but image quality deteriorates due to color deviations from non-uniform light absorption across wavelengths
Solution Approach 1:
The patent modifies the geometric parameters of the light-guiding elements (such as grating period, depth, width, or prism angle) to compensate for the wavelength-dependent absorptivity and transmittance of the polymer material. By adjusting these parameters, the optical path differences for different wavelengths are equalized, reducing color deviations and improving image quality while maintaining the cost advantages of polymer fabrication.
3Manufacturing precision
If light-guiding elements with opposite transmittance trend are introduced, then color uniformity is improved by balancing absorptivity across wavelengths, but device complexity increases
Solution Approach 1:
The patent divides the waveguide structure into multiple functional segments: the polymer waveguide body and the light-guiding elements formed on its surface. Each segment performs a specific function - the waveguide body provides the optical path, while the light-guiding elements (gratings or prisms) provide wavelength compensation. This segmentation allows independent optimization of each component while achieving overall color uniformity, balancing performance improvement with manageable structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design reduces color deviation and enhances color uniformity of the image beam, providing a better viewing experience by maintaining consistent light absorptivity across different wavelengths.
Implementation Method 1
The first light-guiding element and the multiple second light-guiding elements is a partially transmissive and partially reflective layer
Implementation Method 2
An optical waveguide used in the near-eye display is a key element in combining a virtual image and a real image
Data Source
AI summary
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.