Diffractive Grating Index Zoning for Uniform AR Waveguide Output
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Solution Overview
Problem
Current augmented and virtual reality displays face challenges in achieving a wider field of view, higher refractive index, and efficient light propagation due to design complexities in waveguides, which limit their performance in providing uniform displays.
Innovation Solution
The use of optical elements with diffractive gratings that incorporate microheaters and varying ratios of materials with different refractive indices, allowing for selective modulation of refractive indexes to optimize light propagation and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the refractive index of the waveguide is increased to improve light propagation efficiency and field of view, then the design complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent applies local quality by creating zones with different refractive indices within the waveguide structure. Specifically, the waveguide includes a first zone with a first refractive index and a second zone with a second refractive index, where the refractive indices differ to optimize light propagation in different regions. This allows high light efficiency without requiring the entire waveguide to have uniformly high refractive index, thereby reducing manufacturing complexity.
Solution Approach 2:
The patent employs composite materials by combining multiple materials with different refractive indices within the waveguide structure. The waveguide comprises a first material for the first zone and a second material for the second zone, creating a composite structure that optimizes optical performance while managing design and manufacturing complexity through material selection.
2Stability of the object's composition
If the refractive index is increased uniformly along the waveguide length, then display uniformity improves, but light loss increases as light exits the waveguide
Solution Approach 1:
The patent implements local quality by varying the refractive index along the waveguide length through distinct zones. The first zone has a different refractive index than the second zone, allowing optimization of light confinement in early regions while reducing light extraction losses in later regions. This spatial variation maintains display uniformity where needed while minimizing energy loss in other regions.
Solution Approach 2:
The patent applies dynamics by creating a non-uniform, spatially varying refractive index profile along the waveguide. Rather than a static uniform index, the refractive index changes dynamically across different zones and positions, allowing the waveguide to adapt light propagation characteristics to different operational requirements at different locations.
3Area of stationary object
If diffractive gratings are used to widen field of view, then angular resolution improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by implementing diffractive gratings with spatially varying characteristics. The grating period, depth, or orientation varies across different zones of the waveguide, allowing optimization of field of view in different angular regions while managing manufacturing precision requirements through localized rather than uniformly high precision requirements.
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
Enhances the efficiency and performance of waveguides by gradually modulating refractive indices, improving light distribution and reducing losses, thereby enhancing the display quality in augmented and virtual reality systems.
Implementation Method 1
a plurality of voltages is applied to the plurality of microheaters to selectively modulate respective refractive indexes of corresponding portions of the diffractive grating
Implementation Method 2
The optical element may comprise a diffractive grating and a plurality of microheaters corresponding to respective portions of the diffractive grating, wherein a plurality of voltages is applied to the plurality of microheaters to selectively modulate respective refractive indexes of corresponding portions of the diffractive grating. The optical element may be configured to convert the image beam into an output image by diffracting the image beam through the diffractive grating
Implementation Method 3
Light propagating inside the waveguide follows Total Internal Reflection (TIR), and the TIR angle is governed by the refractive index of the waveguide
Data Source
AI summary
Head-mounted displays (HMD) or other suitable optical equipment with waveguides comprising an optical element comprising a diffractive grating having a plurality of zones. The plurality of zones may comprise a first zone, a second zone and a third zone. Substantially all of a plurality of structures defining the first zone may comprise a first material, substantially all of a plurality of structures defining the third zone comprises a second material, a plurality of structures defining the second zone comprises each of the first material and the second material, and a refractive index of the second material may be higher than a refractive index of the first material.