Anamorphic Waveguide Illumination for Wide-FOV AR Eyebox Expansion
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Solution Overview
Problem
Existing near-eye display apparatuses for augmented and virtual reality struggle with achieving wide fields of view, high brightness, and large eyebox sizes while maintaining low weight and cost, and often suffer from image distortions and glare.
Innovation Solution
An anamorphic near-eye display apparatus with a spatial light modulator and optical system featuring transverse and lateral anamorphic components, an extraction waveguide, and polarization-sensitive reflectors, which utilize polarization conversion retarders and extraction features to guide light efficiently and expand the exit pupil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional AR/VR optical systems are used, then image quality can be achieved, but field of view is limited and eyebox size is small
Solution Approach 1:
The optical system is segmented into multiple functional components: waveguide for light propagation, extraction features for pupil expansion, anamorphic components for field of view enhancement, and polarization-sensitive reflectors for directional control. Each component performs a specific function, collectively achieving large eyebox and wide field of view without requiring a single complex optical element.
Solution Approach 2:
The extraction features utilize the third dimension (depth) by creating three-dimensional microstructures within the waveguide. These features extract light in multiple directions simultaneously, expanding the exit pupil size in both lateral and vertical dimensions, thereby achieving large eyebox without increasing the overall footprint of the device.
2Illumination intensity
If high brightness and wide field of view are achieved, then image quality improves, but manufacturing cost and complexity increase
Solution Approach 1:
The system replaces complex mechanical optical assemblies with integrated photonic structures fabricated using semiconductor manufacturing techniques. The waveguide with embedded extraction features and anamorphic components can be manufactured using standard PCB or semiconductor fabrication processes, significantly reducing manufacturing cost compared to traditional precision optical mechanical assemblies.
Solution Approach 2:
The optical properties of the waveguide material are optimized by adjusting parameters such as refractive index, thickness, and extraction feature geometry. These parameter changes enable control over light propagation, extraction efficiency, and field of view, allowing high brightness and wide field of view to be achieved through material and structural optimization rather than complex optical components.
3Area of stationary object
If anamorphic components are added to expand field of view, then lateral and vertical FOV improve, but optical system complexity increases
Solution Approach 1:
The anamorphic components are merged directly into the waveguide structure, eliminating the need for separate external optical elements. The waveguide itself serves as both the light propagation medium and the anamorphic transformation element, reducing the total component count while maintaining wide field of view performance.
Solution Approach 2:
The waveguide performs multiple functions simultaneously: light propagation from the display element, anamorphic transformation for field of view expansion, and pupil expansion through extraction features. This multi-functionality reduces the need for dedicated components for each function, thereby reducing overall system complexity.
4Loss of energy
If polarization-sensitive reflectors are used for light direction, then light efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The polarization-sensitive reflectors are designed to automatically orient themselves relative to the incident light based on the waveguide's structural geometry. The reflector orientation is determined by the waveguide fabrication process itself, allowing the system to self-align without requiring high-precision manual adjustment or complex alignment mechanisms during assembly.
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 apparatus provides wide field of view with high brightness and efficiency, reduced color blur, and increased eyebox size, achieving high image luminance uniformity and comfort with reduced manufacturing complexity and cost.
Implementation Method 1
the polarization conversion retarder is arranged to convert a polarization state of light passing therethrough between a linear polarization state and a circular polarization state
Implementation Method 2
a light reversing reflector that is arranged to reflect light guided along the extraction waveguide in the first direction to form light that is guided along the extraction waveguide in a second direction opposite to the first direction
Implementation Method 3
the polarization-sensitive reflector is arranged to reflect light guided in the first direction having the input linear polarization state and to pass light guided in the second direction having the orthogonal linear polarization state
Implementation Method 4
the array of extraction features is arranged to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer through the front guide surface
Implementation Method 5
a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction
Implementation Method 6
a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide being arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction
Data Source
AI summary
An anamorphic directional illumination device may provide a near-eye display apparatus or a vehicle external light device. The anamorphic near-eye display apparatus includes an illumination system including a spatial light modulator, an optical system including a transverse anamorphic component, an extraction waveguide including a polarization-sensitive reflector and an array of extraction features, a lateral anamorphic component, a light reversing reflector, and a polarisation conversion retarder disposed between a polarisation-sensitive reflector and the light reversing reflector. The polarisation conversion retarder has a retardance of a quarter wavelength at a wavelength of visible light. A thin, transparent and efficient anamorphic display apparatus for Augmented Reality and Virtual Reality displays and for scene illumination is provided.