Crossed-Grating Waveguide Multiplexer for Wider AR Eye Box
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Solution Overview
Problem
Existing augmented reality (AR) technologies face challenges in providing a comfortable and natural-feeling presentation of virtual image elements amidst real-world imagery due to the complexity of the human visual system, particularly in simulating realistic depth perception.
Innovation Solution
A two-dimensional waveguide light multiplexer is introduced, utilizing crossed diffraction gratings on the top and bottom surfaces of a waveguide, allowing for the distribution and outcoupling of light in two dimensions, which can enhance the presentation of virtual content in AR devices by efficiently directing light signals to achieve a wide field-of-view and realistic depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional light multiplexing methods are used in AR devices, then the device structure remains simple, but the field-of-view is limited and depth perception is unrealistic
Solution Approach 1:
The patent applies crossed diffraction gratings arranged in perpendicular directions (x and y dimensions) to achieve two-dimensional light distribution. This dimensional expansion allows the optical element to direct light across a wider angular range, thereby expanding the field-of-view without requiring multiple separate optical components stacked in series.
Solution Approach 2:
The optical element is segmented into multiple diffraction gratings with different grating directions (first grating in x-direction, second grating in y-direction). Each grating segment handles light distribution in its specific direction, and their combined effect achieves comprehensive two-dimensional light control, resolving the contradiction between simplicity and performance.
2Area of stationary object
If conventional outcoupling methods are used, then the optical system remains simple, but the eye box size is limited
Solution Approach 1:
The patent introduces a second diffraction grating oriented perpendicular to the first grating, enabling light to be outcoupled in both horizontal and vertical directions. This two-dimensional outcoupling approach expands the effective eye box area, allowing users to view the virtual image from a broader range of positions without requiring additional waveguides or complex optical paths.
3Manufacturing precision
If simple light distribution is used, then the device remains compact, but realistic depth perception cannot be achieved
Solution Approach 1:
The patent employs diffraction gratings with locally optimized properties, including asymmetric grating profiles and position-dependent grating parameters. These local variations in grating structure enable precise control over light distribution angles and intensities, creating accurate depth cues for different regions of the virtual image to enhance depth perception realism.
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 enables a more comfortable and realistic presentation of virtual content in AR systems by effectively distributing light in two dimensions, enhancing the user's perception of depth and providing a larger eye box, thus improving the overall AR experience.
Implementation Method 1
at least one or more first diffraction gratings having a grating direction, the one or more first diffraction gratings disposed on a major surface of the waveguide, and at least one or more second diffraction gratings having a grating direction, the one or more second diffraction gratings disposed with respect to the one or more first diffraction gratings such that the grating direction of the one or more first diffraction gratings is perpendicular to the grating direction of the one or more second diffraction gratings
Implementation Method 2
a waveguide, at least one or more first diffraction gratings having a grating direction, the one or more first diffraction gratings disposed on a major surface of the waveguide
Data Source
AI summary
A two-dimensional waveguide light multiplexer can efficiently multiplex and distribute a light signal in two dimensions. An example of a two-dimensional waveguide light multiplexer can include a waveguide, a first diffraction grating, and a second diffraction grating arranged such that the grating direction of the first diffraction grating is perpendicular to the grating direction of the second diffraction grating. In some examples, the first and second diffraction gratings are on opposite sides of a waveguide. In some examples, the first and second diffraction gratings are on a same side of a waveguide, with the second grating over the first grating.