AR Waveguide Grating Duty Cycle Control for Outcoupling
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Solution Overview
Problem
Augmented reality waveguides face challenges in controlling the out-coupling strength of virtual images overlaid on ambient environments, as existing technologies struggle to adequately manage the intensity and viewing angle of virtual images due to inconsistent light coupling through surface relief gratings.
Innovation Solution
The implementation of augmented waveguide regions with multiple gratings having different duty cycles and refractive indices, formed using sol-gel solutions and nanoparticle materials like SiO2, SiOC, ZrO2, and TiO2, which are deposited and imprinted to control light modes and intensity distribution, allowing for precise modulation of the field of view and increased viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If surface relief gratings are used to couple light into and out of augmented waveguide combiners, then light coupling is achieved, but the intensity of the out-coupled light cannot be adequately controlled
Solution Approach 1:
The patent applies local quality by varying the duty cycle of surface relief gratings at different positions along the waveguide. Specifically, the grating duty cycle is changed from 0.25 to 0.5 in the second portion of the waveguide, creating localized differences in light coupling strength. This allows different regions of the waveguide to have different out-coupling characteristics, enabling control over the intensity distribution of the augmented reality display without requiring a completely complex grating structure throughout the entire device.
2Adaptability or versatility
If virtual images are overlaid on ambient environment, then augmented reality display is achieved, but the viewing angle is limited
Solution Approach 1:
The patent applies parameter changes by modifying the duty cycle parameter of the surface relief gratings along the length of the waveguide. By transitioning from a first duty cycle (0.25) in the first portion to a second duty cycle (0.5) in the second portion, the system optimizes light coupling to maintain adequate light intensity while expanding the viewing angle. This parameter variation allows the waveguide to achieve both wide viewing angles and reliable light intensity maintenance throughout the display path.
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 solution effectively modulates the field of view and increases the viewing angle by controlling the intensity of out-coupled light, ensuring that the virtual image is optimally displayed without depleting the light intensity before reaching the end of the waveguide region, thereby enhancing the augmented reality experience.
Implementation Method 1
Light is coupled into and out of augmented waveguide combiners using surface relief gratings
Implementation Method 2
Generated light is in-coupled into an augmented waveguide combiner, propagated through the augmented waveguide combiner, out-coupled from the augmented waveguide combiner
Data Source
AI summary
Embodiments described herein relate to augmented waveguide regions. The augmented waveguide regions generally include pluralities of gratings having duty cycles and refractive indices. In certain embodiments, the duty cycles are different, the refractive indices are different, or both the duty cycles and the refractive indices are different. Also described herein are methods for forming the augmented waveguide regions.