Dynamically Addressable Diffractive Optical Elements for AR Waveguides
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Solution Overview
Problem
Augmented reality (AR) devices with static or non-uniform diffractive optical elements (DOEs) suffer from inefficiencies in light projection, leading to wasted light and reduced image clarity due to the need for oversized eye boxes to accommodate varying user positions and face shapes, resulting in diminished image brightness and stray light artifacts.
Innovation Solution
Implementing dynamically adjustable diffractive optical elements (DOEs) that can change diffraction efficiency in response to stimuli, allowing light to be directed only towards the user's eye position, reducing unnecessary illumination and minimizing stray light by using eye-tracking data to control the diffraction efficiency of output and fold DOEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static or non-uniform diffractive optical elements are used, then the eye box can accommodate varying user positions, but light projection efficiency decreases and stray light artifacts increase
Solution Approach 1:
The patent implements dynamically adjustable diffractive optical elements (DOEs) that can change their diffraction efficiency in real-time based on detected eye position. This allows the system to adapt to varying user positions while maintaining high light projection efficiency by directing light only toward the actual eye location rather than illuminating the entire eye box uniformly.
Solution Approach 2:
The patent changes the diffraction efficiency parameter of the DOEs dynamically based on eye position detection. By adjusting this optical parameter in response to user position, the system maintains adaptability to different eye locations while optimizing light projection efficiency and reducing stray light artifacts.
2Adaptability or versatility
If oversized eye boxes are used to accommodate varying user positions, then adaptability improves, but image brightness decreases and stray light artifacts increase
Solution Approach 1:
The patent applies local quality by concentrating light illumination specifically at the location where the user's eye is detected, rather than uniformly illuminating the entire eye box. This creates high illumination intensity at the target location while reducing stray light in other areas, thereby maintaining image brightness and reducing artifacts while still accommodating varying user positions.
Solution Approach 2:
The system dynamically adjusts the illumination pattern and diffraction efficiency of DOEs based on real-time eye position detection. This allows the bright spot to track the user's eye movement, maintaining high image brightness at the correct location while adapting to different user positions and face shapes.
3Ease of manufacture
If uniform diffraction efficiency is used across all DOEs, then manufacturing is simplified, but light is wasted and image clarity diminishes
Solution Approach 1:
The patent implements spatially varying diffraction efficiency parameters across different DOEs, allowing each element to be optimized for its specific location and function. This enhances image clarity and reduces light waste by directing light precisely where needed, while the underlying fabrication processes remain compatible with standard manufacturing techniques.
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 approach increases the efficiency of light projection, reduces optical power requirements, and enhances image clarity by directing light only where needed, minimizing stray light and eliminating the need for air gaps between color-specific DOEs, thereby improving the overall display performance.
Implementation Method 1
Diffractive optical elements (DOE), such as diffraction gratings, operate by diffracting light and are utilized to control the intensity and direction of light
Implementation Method 2
the light propagates within the waveguide through total internal reflection (TIR)
Data Source
AI summary
A waveguide includes a waveguide body including an optically transmissive material having a refractive index different from a surrounding medium and defining an output surface. The waveguide body is configured to propagate light by total internal reflection in one or more directions substantially tangential to the output surface. The waveguide includes one or more diffractive optical elements (DOEs), each configured to change its diffraction efficiency in response to a respective stimulus, and a DOE driver configured to provide the stimuli to each of the DOEs independently.