Optical Waveguide Beam Uniformity via Segmented Regions
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Solution Overview
Problem
Current head-mounted display devices using waveguide elements suffer from non-uniform image transmission due to varying numbers of total reflections, leading to larger spacings between image beams, which results in lower image quality and a smaller eyebox, especially when the field of view is large or the waveguide is thicker, making it difficult to achieve a large viewing angle.
Innovation Solution
An optical waveguide with a first and second optical region, featuring a plate body with first light-guiding optical elements and optical coupling-out structures, where the image beam is separated into sub-image beams through total reflection, increasing their density and uniformity, allowing for full reflection and improved transmission to the second optical region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the waveguide plate is thicker or the field of view is larger, then the optical path length increases, but the spacing between image beams becomes larger causing non-uniform image transmission
Solution Approach 1:
The waveguide plate is divided into multiple optical regions (first optical region with light-guiding optical elements and second optical region with coupling-out structures). This segmentation allows different zones to perform different functions: the first region manages beam separation and reflection to control spacing, while the second region handles beam output, thereby solving the uniformity issue in thicker waveguides with larger fields of view
2Duration of action of moving object
If the number of total reflections increases, then the light transmission path is extended, but the spacing between image beams with the same information becomes larger reducing eyebox size
Solution Approach 1:
Different optical regions are assigned different functional qualities: the first optical region contains light-guiding optical elements that create varied transmission paths to control beam spacing, while the second optical region contains coupling-out structures optimized for beam extraction. This local differentiation allows the system to maintain appropriate beam spacing throughout the transmission path while preserving adequate eyebox size
3Length of moving object
If the spacing between image beams is larger, then the transmission path is more extended, but the pupils cannot receive the image beams properly reducing image quality
Solution Approach 1:
Light-guiding optical elements are introduced as intermediary components within the waveguide plate to mediate the transmission of image beams. These elements actively control the spacing and distribution of beams during transmission, ensuring that even over extended paths, the beams maintain appropriate spacing for proper pupil reception and high image quality
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 configuration enhances the uniformity and density of the image beam, reducing missing blocks or dark areas, resulting in high-quality images with improved uniformity and larger eyebox compatibility for head-mounted display devices.
Implementation Method 1
the sub image beams in the first optical region are transmitted via total reflection to the second optical region
Implementation Method 2
the optical coupling-out structures are disposed in the plate body and are located in the second optical region
Data Source
AI summary
The disclosure provides an optical waveguide, a manufacturing method of an optical waveguide, and a head-mounted display device. The optical waveguide has a first optical region and a second optical region for transmitting an image beam. The optical waveguide includes a plate body, multiple first light-guiding optical elements, and multiple optical microstructures. The first light-guiding optical elements are disposed in parallel lines on a light-guiding plane inside the plate body. The light-guiding plane is located in the first optical region, and there is a spacing between the adjacent first light-guiding optical elements. The image beam transmitted to the light-guiding plane is separated into multiple sub image beams, and the transmission paths of the sub image beams are at least partially different. The optical coupling-out structure is disposed in the plate body and is located in the second optical region.