Wrapped Waveguide for 140-Degree AR Field of View
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Solution Overview
Problem
Optical waveguides in augmented reality devices have limited field of view (FOV) due to the restricted range of internal angles over which light can propagate, resulting in a narrow range of angles exiting the waveguide, which restricts the user's ability to see virtual objects in a wider environment.
Innovation Solution
The use of multiple optical waveguides with diffractive couplers and output couplers, where one waveguide provides a central portion of the image to the user's central vision and another waveguide provides a peripheral portion, allowing for a larger diagonal FOV of up to 140 degrees by projecting light at different central angles of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single optical waveguide is used, then the device structure is simple, but the field of view is limited to less than 40 degrees
Solution Approach 1:
The patent divides the single waveguide system into multiple waveguides (first optical waveguide and second optical waveguide), each handling different angular ranges of light propagation. The first waveguide handles light at lower angles of incidence while the second waveguide handles light at higher angles, thereby segmenting the field of view coverage to achieve a combined FOV exceeding 40 degrees while maintaining manageable structural complexity through modular design
Solution Approach 2:
The patent introduces a second waveguide operating at a different central angle of incidence (second central angle greater than first central angle), adding an angular dimension to the light propagation paths. This dimensional expansion allows the system to capture and display virtual images across a wider range of viewing angles, effectively increasing the field of view by utilizing multiple angular dimensions rather than relying on a single waveguide's limited angular range
2Area of stationary object
If the critical angle is lowered by using reflective coating or higher index of refraction material, then the light propagation angle range increases slightly, but the manufacturing cost increases
Solution Approach 1:
Rather than modifying material properties or adding reflective coatings to a single waveguide, the patent segments the function across multiple waveguides, each optimized for specific angular ranges. This approach achieves expanded light propagation angle range through architectural design rather than material changes, avoiding the increased manufacturing costs associated with specialized coatings or high-index materials
Solution Approach 2:
The patent changes the operational parameters by introducing multiple waveguides with different central angles of incidence, effectively expanding the overall angular coverage. This parameter-based solution (varying angles across multiple components) achieves the goal of increased light propagation angle range without relying on expensive material substitutions or additional reflective coatings
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 configuration significantly expands the field of view without sacrificing high resolution in the direct line of sight, allowing users to see virtual objects in a wider environment while maintaining clarity in central vision.
Implementation Method 1
The first light engine is configured to project light into the first input diffractive coupler at a first central angle of incidence
Implementation Method 2
Light not propagating parallel to the surface will travel along the waveguide bouncing back and forth between the surfaces, so long as the angle of incidence with respect to the surface normal is greater than some critical angle associated with the material from which the optical waveguide is made
Implementation Method 3
The first output coupler is configured to project the light projected into the first input diffractive coupler out of the first optical waveguide
Data Source
AI summary
An apparatus having optical waveguides for providing a large FOV is disclosed. A first light engine projects light into an input diffractive coupler of a first waveguide at a first central angle. An output coupler of the first waveguide projects the light out of the first optical waveguide. A second light engine projects light into an input diffractive coupler of a second waveguide at a second central angle that is greater than the first central angle. An output coupler of the second waveguide projects the light out of the second optical waveguide to intersect with the light projected out of the first optical waveguide. The first waveguide may be used to project a first part of an image into a central portion of a user's vision. The second waveguide may be used to project a second part of the image into a peripheral portion of the user's vision.