Grating Waveguide Layout for Rainbow-Free AR Image Projection
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Solution Overview
Problem
Augmented reality (AR) glasses using grating waveguides suffer from rainbow patterns caused by ambient light diffracted into the eye box, interfering with the viewing experience.
Innovation Solution
The grating waveguide apparatus and system are designed such that the grating vectors form exactly one closed path in k-space, ensuring that the field of view projected by the imaging device remains undistorted and that diffracted ambient light does not enter the eye box, thereby eliminating rainbow patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a grating waveguide is used to guide images into the human eye, then the augmented reality function is achieved, but rainbow patterns are formed by ambient light diffracted into the eye box
Solution Approach 1:
The patent segments the grating structure into multiple regions with different grating vector configurations. Specifically, it divides the grating into a first grating region with first grating vectors and a second grating region with second grating vectors, allowing different regions to handle different light paths separately - one for image guidance and another for ambient light management
Solution Approach 2:
The patent applies local quality by assigning different grating vector properties to different spatial regions. The first grating region has grating vectors configured for efficient image coupling, while the second grating region has grating vectors specifically designed to direct ambient light away from the eye box, creating localized functional optimization
2Object-affected harmful factors
If the grating structure is designed to couple out ambient light, then rainbow patterns are reduced, but the image projection may become distorted
Solution Approach 1:
The patent segments the grating structure into multiple regions with different grating vector configurations. Specifically, it divides the grating into a first grating region with first grating vectors and a second grating region with second grating vectors, allowing different regions to handle different light paths separately - one for image guidance and another for ambient light management
Solution Approach 2:
The patent changes the grating vector parameters spatially across different regions. By varying the grating vector magnitude and direction in different grating regions, the system optimizes for both image fidelity in the first region and ambient light rejection in the second region, preventing image distortion while eliminating rainbow patterns
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 ensures distortion-free image projection and eliminates rainbow patterns, enhancing the viewing experience by allowing only the intended image to be observed through the grating waveguide apparatus.
Implementation Method 1
Light emitted from an optical engine is coupled into the waveguide substrate by the in-coupling grating and propagates within the waveguide substrate via total reflection. Each time the light encounters the out-coupling grating, a portion of the light is coupled out.
Implementation Method 2
Light emitted from an optical engine is coupled into the waveguide substrate by the in-coupling grating and propagates within the waveguide substrate via total reflection.
Data Source
AI summary
The present application provides a grating waveguide apparatus and waveguide system for reducing rainbow patterns. The apparatus includes a waveguide substrate and a grating structure. The grating structure includes a first in-coupling grating and a first out-coupling grating, a grating region of the first out-coupling grating has a grating line overlapping structure with multiple dimensions; or, the grating structure includes a second in-coupling grating, a turning grating and a second out-coupling grating, a grating line region of the turning grating and a grating line region of the second out-coupling grating have an overlapping region; grating vectors of the above-mentioned grating structure form exactly one closed path in k-space.