Beam Replicating Near-Eye Display for Large Eyebox
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Solution Overview
Problem
Head-mounted displays and near-eye displays face a limitation in etendue, which restricts the combination of a large eyebox and field of view, making it difficult to provide immersive virtual or augmented reality experiences while accommodating different user sizes and head shapes.
Innovation Solution
The solution involves an image replicator and a combiner that split and redirect image light beams into a grid-like pattern, expanding the eyebox while preserving the field of view, using waveguides, diffraction gratings, and angular- and wavelength-selective components to ensure image quality and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the eyebox size is increased, then user accommodation freedom is improved, but the field of view becomes narrower
Solution Approach 1:
The patent divides the single optical path into multiple parallel optical paths by splitting the incident beam into multiple beams. Each beam is directed through separate waveguides to create multiple exit pupils, effectively segmenting the optical system to achieve both large eyebox and wide field of view simultaneously
Solution Approach 2:
The patent introduces a spatial dimension by creating multiple parallel optical paths in different spatial locations. By arranging waveguides and beam splitters in a three-dimensional configuration, the system expands the eyebox in one dimension while maintaining field of view through the spatial arrangement of multiple beams
2Area of moving object
If the field of view is widened, then immersion experience is improved, but the eyebox size becomes smaller
Solution Approach 1:
The system segments the optical beam into multiple parallel beams that travel through separate waveguides, creating multiple exit pupils across a large area. This segmentation allows the field of view to be widened while each individual beam maintains proper eyebox size for user accommodation
Solution Approach 2:
The patent creates multiple copies of the optical beam by using beam splitters to divide the incident beam into multiple beams. Each beam is a copy that can be independently directed through waveguides to create multiple virtual images, effectively copying the optical path multiple times to achieve both wide field of view and large eyebox
3Area of stationary object
If multiple beams are created using beam splitters, then eyebox is expanded, but optical loss increases
Solution Approach 1:
The patent replaces traditional beam splitters with waveguide-based optical coupling mechanisms that use total internal reflection and evanescent wave coupling. This substitution reduces optical loss by eliminating the need for high-loss beam splitter interfaces while still achieving beam multiplication and eyebox expansion
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 approach effectively increases the etendue of near-eye displays, allowing for a larger eyebox and maintaining the field of view, enhancing user immersion and convenience by accommodating various user sizes and head shapes.
Implementation Method 1
a waveguide having a first surface and a second surface, the first surface being partially reflective at a wavelength of the image light and the second surface being fully reflective at the wavelength of the image light. The first beam propagates in the waveguide between the first and second surfaces in a zigzag pattern
Implementation Method 2
the first surface being partially reflective at a wavelength of the image light... Each reflection creates a second beam of the plurality of second beams that propagates in a direction parallel to a corresponding direction of the first beam
Implementation Method 3
The combiner may be configured for selectively redirecting rays of the second beams depending on angle of incidence of the rays of the second beams on the combiner
Implementation Method 4
The waveguide may include a diffractive structure for in-coupling the first beam into the waveguide, an out-coupling second beams of the plurality of second beams from the waveguide
Data Source
AI summary
A near-eye display (NED) includes an image replicator and an image combiner. The image replicator is configured for receiving a beam of image light from a source such as an image projector, and splitting the beam into a plurality of second beams of image light. The combiner is configured to relay the plurality of second beams to an eyebox of the NED such that the second beams at the eyebox are laterally offset from one another. The etendue of the NED may be increased by replicating and relaying the image beams.