Stacked Waveguides With Different Gratings for Wider AR Field of View
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Solution Overview
Problem
Existing augmented reality (AR) technologies struggle to provide a comfortable and realistic presentation of virtual image elements amidst real-world imagery due to challenges in matching accommodation and vergence of the human visual system, leading to discomfort and poor depth perception.
Innovation Solution
A stacked waveguide assembly with diffractive devices based on cholesteric liquid crystal (CLC) is employed, which includes multiple waveguides with different diffraction gratings to enhance the combined field of view and simulate three-dimensional imagery by aligning image presentations with the eye's accommodative and convergent states, using total internal reflection (TIR) and switchable diffraction elements to output images at varying depth planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single waveguide with a fixed diffraction grating is used, then the device complexity is reduced, but the field of view and depth perception capability are limited
Solution Approach 1:
The optical device is divided into multiple waveguides (first waveguide, second waveguide, etc.), each with its own diffraction grating optimized for specific viewing angles. This segmentation allows each waveguide to handle a portion of the total field of view, collectively providing a broader combined field of view and improved depth perception without requiring a single complex waveguide structure
Solution Approach 2:
Multiple waveguides are stacked in an overlapping configuration where they share common optical paths and exit pupils. The waveguides are arranged such that they nest within each other's optical footprint, allowing compact integration while maintaining independent diffraction grating structures for expanded angular coverage
2Adaptability or versatility
If multiple waveguides with different diffraction gratings are stacked to expand field of view, then the combined field of view increases, but the device complexity increases
Solution Approach 1:
Multiple waveguides with different diffraction gratings are combined in a stacked configuration where their optical paths merge at the exit pupil. Each waveguide contributes a specific angular range to the combined field of view, and their merging creates a unified optical output that provides expanded total field of view while maintaining manageable individual component complexity
Solution Approach 2:
The field of view expansion is achieved by adding the vertical stacking dimension to the traditional planar waveguide configuration. By arranging waveguides in multiple layers along the vertical axis with different diffraction grating orientations, the system expands the angular coverage in three dimensions without significantly increasing the lateral footprint of each individual waveguide
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 provides a more realistic and comfortable AR experience by aligning image presentations with the human visual system's accommodation and vergence, enhancing depth perception and reducing discomfort, while allowing simultaneous viewing of virtual and real-world elements.
Implementation Method 1
the diffraction gratings are configured to diffract visible light incident thereon into the respective waveguides
Implementation Method 2
such that visible light diffracted into the respective waveguides propagates therewithin
Data Source
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AI summary
In one aspect, an optical device comprises a plurality of waveguides formed over one another and having formed thereon respective diffraction gratings, wherein the respective diffraction gratings are configured to diffract visible light incident thereon into respective waveguides, such that visible light diffracted into the respective waveguides propagates therewithin. The respective diffraction gratings are configured to diffract the visible light into the respective waveguides within respective field of views (FOVs) with respect to layer normal directions of the respective waveguides. The respective FOVs are such that the plurality of waveguides are configured to diffract the visible light within a combined FOV that is continuous and greater than each of the respective FOVs.