Crossed-Grating Waveguide Multiplexer for 2D Light Distribution
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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 employed, utilizing crossed gratings on a waveguide to distribute light in two dimensions, allowing for efficient multiplexing of optical signals and enhancing the presentation of virtual content in AR devices, which includes a stacked waveguide assembly with multiple depth planes to simulate realistic depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single optical signal is transmitted through the waveguide using conventional diffraction gratings, then the device structure is simple, but the light distribution efficiency and field of view are limited
Solution Approach 1:
The patent transitions from conventional single-direction diffraction gratings to two-dimensional crossed gratings that diffract light in both x and y directions simultaneously. This dimensional expansion enables the waveguide to distribute light across a broader angular range, significantly improving light distribution efficiency and field of view without requiring multiple separate optical paths
Solution Approach 2:
The patent combines multiple diffraction functions into a single integrated crossed grating structure. By overlaying orthogonal grating patterns (one set of lines in x-direction, another set in y-direction), the system merges what would traditionally require separate optical elements into one compact component, maintaining structural simplicity while achieving enhanced light distribution
2Manufacturing precision
If conventional diffraction gratings are used for light multiplexing, then the device is easier to manufacture, but the simulation of realistic depth perception and three-dimensional imagery is insufficient
Solution Approach 1:
The crossed grating structure introduces two-dimensional spatial control over light propagation, enabling precise manipulation of light paths in both horizontal and vertical planes. This dimensional control allows for the creation of multiple depth planes within the waveguide assembly, providing accurate simulation of three-dimensional imagery and realistic depth perception
Solution Approach 2:
The patent employs a stacked waveguide assembly where each waveguide layer can be independently configured with specific grating patterns and orientations. This segmentation allows each layer to handle specific depth planes or angular ranges, and the cumulative effect of multiple layers creates a comprehensive three-dimensional visual experience with high depth perception accuracy
3Use of energy by moving object
If the waveguide thickness is increased to improve light in-coupling, then more light can be guided, but the device size and weight increase
Solution Approach 1:
The crossed grating structure enhances light coupling efficiency by utilizing two-dimensional diffraction to redirect light into the waveguide. This approach maximizes the use of available light from the source by capturing light over a broader angular range and directing it into the waveguide core, thereby improving coupling efficiency without requiring increased waveguide dimensions
Solution Approach 2:
The patent optimizes the grating parameters (period, depth, orientation) of the crossed gratings to achieve maximum light coupling efficiency at the existing waveguide thickness. By carefully tuning these parameters, the system extracts the maximum light guidance capability from the current device geometry, avoiding the need to increase thickness and thereby preventing additional weight
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 realistic and comfortable simulation of three-dimensional imagery by aligning gratings to distribute light in two dimensions, improving the integration of virtual content with real-world elements and expanding the field of view, thus enhancing the AR experience.
Implementation Method 1
an outcoupling optical element comprising a diffraction grating with a grating direction, and an incoupling optical element with another grating direction
Implementation Method 2
configured to incouple the light into the waveguide such that the light is guided within the waveguide to the outcoupling optical element
Data Source
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AI summary
A two-dimensional waveguide light multiplexer is described herein that 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 disposed above the first diffraction grating and arranged such that the grating direction of the first diffraction grating is perpendicular to the grating direction of the second diffraction grating. Methods of fabricating a two-dimensional waveguide light multiplexer are also disclosed.