AR Eyepiece Waveguide Grating Layout for Wider FOV and 3D Comfort
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Solution Overview
Problem
Existing augmented reality (AR) systems face challenges in efficiently expanding the field of view (FOV) and providing a realistic, comfortable three-dimensional image simulation due to limitations in waveguide design, leading to discomfort and suboptimal depth perception.
Innovation Solution
The development of an eyepiece waveguide for AR systems featuring an optically transmissive substrate with input coupling and combined pupil expander-extractor grating regions, configured to alter and out-couple light beams efficiently, and incorporating recycler gratings to enhance FOV and depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional waveguide designs are used, then the device complexity is reduced, but the field of view expansion and depth perception quality deteriorate
Solution Approach 1:
The waveguide is segmented into distinct functional regions: input coupling grating (ICG) region for light entry, combined pupil expander-extractor (CPE) grating region for beam manipulation, and recycler grating region for light redirection. Each region contains specific diffractive features that perform dedicated functions, allowing complex optical operations to be distributed across modular segments rather than requiring a monolithic complex structure
Solution Approach 2:
The patent employs multiple diffractive features arranged in rows and columns of alternating higher and lower quadrilateral surfaces, creating a three-dimensional diffractive structure on the waveguide surface. This dimensional complexity enables multiple light interactions (first interaction for propagation direction alteration, second interaction for out-coupling) within a compact footprint, achieving enhanced FOV and depth perception without proportionally increasing overall device complexity
2Productivity
If simple grating structures are used, then the manufacturing precision requirements are reduced, but the light propagation efficiency and FOV expansion capability deteriorate
Solution Approach 1:
The combined pupil expander-extractor (CPE) grating region merges two functions into a single integrated structure: pupil expansion (altering propagation direction) and pupil extraction (out-coupling light from waveguide). The diffractive features perform both functions through sequential interactions, eliminating the need for separate grating structures and reducing overall manufacturing complexity while maintaining high light propagation efficiency
Solution Approach 2:
The recycler grating region is positioned at a specific location within the waveguide to redirect straying light beams back toward the CPE grating region. By changing the spatial parameter (position) and orientation parameter (angle) of the recycler grating, the system recovers light that would otherwise be lost, improving overall productivity without requiring higher manufacturing precision in the primary grating structures
3Ease of operation
If conventional optical paths are used, then the device complexity is minimized, but the accommodation-vergence reflex alignment and user comfort deteriorate
Solution Approach 1:
The recycler grating region acts as a feedback mechanism that captures light beams straying from the optimal optical path and redirects them back toward the CPE grating region. This feedback loop ensures that more light reaches the intended exit pupil, improving image quality and user comfort by aligning the optical path with the accommodation-vergence reflex, while the feedback mechanism itself adds minimal structural complexity
Solution Approach 2:
The CPE grating region serves as an intermediary structure between the ICG region and the exit pupil. It mediates the light transformation process by first altering propagation directions (pupil expansion) and then out-coupling the beams (pupil extraction). This intermediary structure enables precise control over the optical path to match human visual physiology requirements without requiring direct complex configuration of all optical components
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 enhances the field of view and improves the realism and comfort of three-dimensional image simulation by optimizing light propagation and distribution within the eyepiece waveguide, aligning with the accommodation-vergence reflex for a more immersive AR experience.
Implementation Method 1
an input coupling grating (ICG) region formed on or in one of the surfaces of the substrate, the ICG region being configured to receive a beam of light and to couple the beam into the substrate in a guided propagation mode
Implementation Method 2
the first CPE grating region comprising a plurality of diffractive features configured to alter the propagation direction of the beam with a first interaction, and to out-couple the beam from the eyepiece waveguide with a second interaction
Data Source
AI summary
An eyepiece waveguide for an augmented reality display system. The eyepiece waveguide can include an optically transmissive substrate with an input coupling grating (ICG) region. The ICG region can receive a beam of light and couple the beam into the substrate in a guided propagation mode. The eyepiece waveguide can also include a combined pupil expander-extractor (CPE) grating region that receives the beam of light from the ICG region and alters the propagation direction of the beam with a first interaction and out-couples the beam with a second interaction. The diffractive features of the CPE grating region can be arranged in rows and columns of alternating higher and lower quadrilateral surfaces or the diffractive features can comprise diamond shaped raised ridges. The eyepiece waveguide can also include one or more recycler grating regions.