Multi-Layer Diffractive Grating for AR Depth Perception
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional augmented reality and virtual reality systems face challenges in creating a comfortable, natural-feeling, rich presentation of virtual image elements among real-world imagery, particularly in achieving a true sensation of depth, which can lead to unstable imaging, eye strain, and lack of surface depth due to accommodation conflicts in the human visual system.
Innovation Solution
The implementation of a diffraction structure with a waveguide substrate, an underlayer, and a top grating surface, where each layer has a distinct refractive index, allowing for increased diffraction efficiency and a larger field of view, counteracting the reduction in diffraction efficiency with angle, and enabling multiple focal planes for enhanced depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer diffractive grating structure is used, then the device complexity is reduced, but the diffraction efficiency decreases at oblique angles and the field of view is limited
Solution Approach 1:
The diffractive grating structure is segmented into multiple layers (first grating layer, second grating layer, and intermediate layer) with different refractive indices. Each layer contributes to the overall diffraction function, allowing the system to maintain high diffraction efficiency across a broader angular range while managing complexity through functional decomposition
Solution Approach 2:
The patent employs composite material structures with layers having different refractive indices (n1, n2, n3) to create a diffractive optical element that optimizes light diffraction. The composite structure combines materials with specific optical properties to achieve superior performance compared to single-material gratings, particularly in maintaining efficiency at oblique incidence angles
2Manufacturing precision
If a single focal plane is used in the display system, then the optical system is simpler, but the depth perception and accommodation response are insufficient
Solution Approach 1:
The patent implements a variable focus optical system that can dynamically adjust between multiple focal planes. This allows the display to present content at different depths (e.g., near field and far field simultaneously), enabling the human visual system to achieve proper accommodation response and perceive true depth, while the system adapts its optical configuration based on viewing requirements
Solution Approach 2:
The optical system extends from a single focal plane to multiple focal planes along the optical axis, adding a depth dimension to the display capability. This multi-planar approach allows virtual content to be presented at different distances from the viewer, creating a more realistic three-dimensional viewing experience that engages the accommodation-convergence coupling of the human visual system
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
This configuration provides an increased field of view and improved depth perception, reducing eye strain and enhancing the comfort and ergonomics of virtual and augmented reality experiences by accurately simulating surface depth through varied focal planes.
Implementation Method 1
a diffractive optical element (DOE) to receive the light associated with the one or more frames of image data and direct the light to the user's eyes, the DOE comprising a diffraction structure
Implementation Method 2
a waveguide substrate corresponding to a waveguide refractive index
Data Source
AI summary
Disclosed is an improved diffraction structure for 3D display systems. The improved diffraction structure includes an intermediate layer that resides between a waveguide substrate and a top grating surface. The top grating surface comprises a first material that corresponds to a first refractive index value, the underlayer comprises a second material that corresponds to a second refractive index value, and the substrate comprises a third material that corresponds to a third refractive index value.