Anamorphic Near-Eye Display Waveguide for Larger Eyeboxes
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Solution Overview
Problem
Existing near-eye display apparatuses face challenges in achieving a thin form factor, large eyebox size, high resolution, and wide field of view while maintaining high luminance and contrast, with issues related to image distortions and stray light glare, particularly in augmented reality displays.
Innovation Solution
An anamorphic near-eye display apparatus with an optical system having anamorphic properties in lateral and transverse directions, utilizing a spatial light modulator, extraction waveguide, and light reversing reflector to provide exit pupil expansion and correct for ophthalmic conditions, with extraction features designed to enhance image focus and reduce complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a waveguide optical system is used to reduce form factor and weight, then the device size and weight are reduced, but achieving large eyebox size and wide field of view becomes more difficult
Solution Approach 1:
The patent applies anamorphic optical properties that differ in lateral and transverse directions. The extraction waveguide uses asymmetric extraction features with different dimensions and orientations to expand the eyebox in specific directions while maintaining a compact overall form factor. This dimensional differentiation allows the system to achieve large eyebox size without proportionally increasing the waveguide volume.
2Manufacturing precision
If high resolution and wide field of view are achieved, then image quality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The extraction waveguide is divided into multiple discrete extraction features distributed across the waveguide structure. Each extraction feature can be independently designed and manufactured with specific geometric parameters to control light extraction at different locations. This segmentation allows for modular manufacturing processes and simplifies the production of high-precision optical systems by breaking down complex monolithic structures into manageable components.
3Area of stationary object
If light extraction features are added to the waveguide, then exit pupil expansion is achieved, but image distortions and stray light glare increase
Solution Approach 1:
The extraction features are designed with spatially varying properties including different sizes, shapes, orientations, and extraction depths at different locations within the waveguide. This local differentiation optimizes light extraction efficiency in specific regions while controlling stray light generation in other regions. The asymmetric design of extraction features allows selective extraction of useful light while minimizing the generation of harmful stray light and glare.
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 achieves sharp virtual images at a finite viewing distance, corrects for ophthalmic conditions, reduces image blur, and enhances viewing comfort with a large eyebox and high image quality over a wide field of view, while minimizing manufacturing complexity and cost.
Implementation Method 1
an extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide
Implementation Method 2
a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction
Implementation Method 3
the extraction features being arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction
Data Source
AI summary
An anamorphic near-eye display apparatus comprises a spatial light modulator with anamorphic pixels; an input transverse anamorphic lens; and an extraction waveguide comprising a lateral anamorphic light reversing reflector. Light from the first spatial light modulator is imaged in the transverse direction by the transverse anamorphic lens, is input into the extraction waveguide and is guided in a first direction along the extraction waveguide. The light is imaged by the lateral anamorphic mirror in the lateral direction and directed in a second direction back through the extraction waveguide. Light extraction features are arranged to direct the reflected light towards the pupil of a viewer. The light extraction features are provided with optical power so that for each point on the spatial light modulator, the output light diverges towards the eye of a viewer. A virtual image plane at a finite viewing distance and correction for ophthalmic conditions may be provided. An efficient near-eye display apparatus for Augmented Reality and Virtual Reality displays is provided.