Waveguide Output Coupler Grating Layout for Uniform AR Light Extraction
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Solution Overview
Problem
Existing waveguide-based optical systems for augmented reality devices face limitations in viewing angle, size reduction, and light uniformity, leading to deteriorated image quality.
Innovation Solution
A waveguide optical device with a structure featuring input and output couplers having spaced-apart grating regions, arranged in concentric semicircular patterns and varying diffraction efficiencies, to enhance light uniformity and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If free-curved surface reflection or multi-mirror reflection is used to input light into the waveguide, then the structure is simple and optical transmission efficiency is high, but the viewing angle is limited and the size of the waveguide cannot be reduced
Solution Approach 1:
The patent replaces mechanical reflection systems (free-curved surface reflection or multi-mirror reflection) with a diffractive optical element-based system. The input coupler uses diffraction gratings to couple light into the waveguide, substituting the mechanical reflection approach with an optical diffraction mechanism, thereby achieving both compact size and expanded viewing angle
Solution Approach 2:
The patent changes the optical coupling parameters by using diffractive elements with specific grating periods and structures. By adjusting the diffraction grating parameters (period, depth, shape), the system achieves efficient light coupling while enabling broader viewing angles and smaller waveguide dimensions compared to traditional reflection-based systems
2Loss of energy
If free-curved surface reflection or multi-mirror reflection is used to input light into the waveguide, then the structure is simple and optical transmission efficiency is high, but the size of the waveguide cannot be reduced
Solution Approach 1:
The patent replaces mechanical reflection systems with a diffractive optical element-based system. The input coupler uses diffraction gratings to couple light into the waveguide, substituting the mechanical reflection approach with an optical diffraction mechanism, thereby achieving both compact size and efficient light transmission
Solution Approach 2:
The patent changes the optical coupling parameters by using diffractive elements with specific grating periods and structures. By optimizing the diffraction grating parameters, the system achieves efficient light coupling while enabling smaller waveguide dimensions
3Device complexity
If conventional input couplers are used, then the structure is simple, but the uniformity of light propagating through the waveguide is low and image quality deteriorates
Solution Approach 1:
The patent divides the output coupler into multiple discrete grating regions (first, second, third, and fourth grating regions) with different diffraction efficiencies. This segmentation allows each region to be optimized for specific light propagation directions, improving overall light uniformity while maintaining a manageable structural complexity
Solution Approach 2:
The patent assigns different diffraction efficiencies to different grating regions based on their local requirements. The first and second grating regions have different diffraction efficiencies from the third and fourth grating regions, creating local optimizations that collectively improve light uniformity across the entire waveguide output
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 solution improves light uniformity and reduces the waveguide's size, resulting in enhanced image quality and user convenience for augmented reality applications.
Implementation Method 1
an input coupler configured to input light into the waveguide; and an output coupler configured to output the light propagating in the waveguide to an outside
Implementation Method 2
a waveguide including a first surface, and a second surface opposite to the first surface
Data Source
AI summary
Provided are a waveguide optical device and a near-eye display apparatus including the same. The waveguide optical device includes a waveguide that propagates light, an input coupler that inputs the light into the waveguide, and an output coupler that outputs the light propagating in the waveguide to the outside, wherein the output coupler includes a plurality of grating regions, which are arranged to be spaced apart from each other.