AR Eyepiece Waveguide Gratings for Wide Field and Fewer Artifacts
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Solution Overview
Problem
Existing augmented reality display systems face challenges in efficiently expanding the field of view and maintaining image quality while minimizing artifacts like the 'screen door effect', which affects the user's immersive experience.
Innovation Solution
The eyepiece waveguide incorporates an optically transmissive substrate with input coupling and combined pupil expander-extractor grating regions, featuring diffractive features arranged in rows and columns, to alter and out-couple light beams, enhancing the field of view and reducing artifacts through optimized light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional waveguide designs are used, then the device complexity is reduced, but the field of view expansion capability and image quality deteriorate due to screen door effect artifacts
Solution Approach 1:
The waveguide is segmented into distinct functional regions: an input coupling grating (ICG) region for light entry, and multiple combined pupil expander-extractor (CPE) grating regions for light manipulation. Each region contains specifically arranged diffractive features that perform targeted functions, allowing independent optimization of each segment to reduce artifacts while managing overall complexity
Solution Approach 2:
Different regions of the waveguide are assigned different grating structures with specific properties. The ICG region uses one type of diffractive feature arrangement, while the CPE regions use different arrangements optimized for pupil expansion and extraction. This local differentiation allows each region to address specific optical challenges, improving overall image quality and reducing screen door effects
2Area of moving object
If pupil expansion is increased to expand field of view, then the field of view improves, but image quality and artifact reduction deteriorate
Solution Approach 1:
The patent combines the pupil expander and pupil extractor functions into a single integrated CPE grating region. This merging allows coordinated manipulation of light beams to expand the pupil and field of view while simultaneously maintaining image quality. The combined structure ensures that expansion and extraction operations work together harmoniously rather than creating conflicting optical effects that would generate artifacts
Solution Approach 2:
The diffractive features are arranged in two-dimensional patterns (rows and columns of alternating higher and lower quadrilateral surfaces) rather than simple one-dimensional gratings. This dimensional enhancement provides additional degrees of freedom for controlling light propagation, enabling simultaneous achievement of wide field of view and high image quality by manipulating light in multiple spatial dimensions
3Area of moving object
If multiple diffractive interactions are used to expand pupil, then the field of view expands, but the device complexity increases
Solution Approach 1:
The CPE grating regions are designed to perform multiple functions simultaneously: they act as pupil expanders in one pass and pupil extractors in another pass, and they also serve as out-coupling mechanisms. This multi-functionality reduces the need for separate dedicated components for each function, thereby expanding the pupil and field of view while limiting the increase in device 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 solution provides an expanded field of view with improved image quality and reduced artifacts, resulting in a more immersive and comfortable augmented reality experience for users.
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 an input beam of light and to couple the input beam into the substrate as a guided beam
Implementation Method 2
a first combined pupil expander-extractor (CPE) grating region formed on or in the first surface of the substrate, the first CPE grating region being positioned to receive the guided beam from the ICG region, and 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.