Anamorphic Near-Eye Display Waveguide Architecture
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Solution Overview
Problem
Current near-eye display apparatuses for virtual and augmented reality struggle to provide high-resolution, high-luminance images with wide fields of view while maintaining a thin form factor, low weight, and low manufacturing complexity, while also ensuring high transparency and reducing glare and image distortions.
Innovation Solution
An anamorphic near-eye display apparatus featuring a spatial light modulator with pixels distributed in the lateral direction, an optical system with transverse and lateral anamorphic components, and an extraction waveguide with reflective features that expand the exit pupil, reduce aberrations, and enhance image contrast and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If waveguide types are used to reduce form factor and weight, then compact size and low weight are achieved, but device complexity increases due to optical path folding within the waveguide
Solution Approach 1:
The optical system is segmented into multiple functional waveguide components: an input waveguide for receiving light from the spatial light modulator, an intermediate waveguide for light propagation, and an extraction waveguide for delivering light to the user's eye. Each waveguide segment performs a specific function, allowing the system to achieve compact form factor while managing complexity through modular design
Solution Approach 2:
A polarisation conversion retarder is introduced as an intermediary component between the spatial light modulator and the waveguide system. This retarder converts linearly polarized light to circularly polarized light, enabling efficient light coupling into the waveguide and improving overall system performance while maintaining compact dimensions
2Area of moving object
If exit pupil expansion is implemented, then large eyebox size is achieved, but device complexity increases due to additional optical components
Solution Approach 1:
The extraction waveguide employs a nested structure with multiple reflective extraction features embedded within the waveguide substrate. These features include reflection gratings and reflective surfaces that are integrated into the waveguide's internal architecture, expanding the exit pupil area without significantly increasing the external form factor or overall device complexity
Solution Approach 2:
Reflective extraction features are distributed along the length of the extraction waveguide in a one-dimensional array, creating an extended exit pupil in the lateral direction. This dimensional approach allows large eyebox size to be achieved while maintaining a thin profile perpendicular to the waveguide length
3Manufacturing precision
If high resolution and wide field of view are provided, then image quality is improved, but manufacturing complexity increases
Solution Approach 1:
The spatial light modulator serves multiple functions simultaneously: it generates high-resolution images, controls the angular distribution of light rays to achieve wide field of view, and interfaces with the waveguide system through polarisation conversion. This multi-functionality reduces the need for separate components, simplifying manufacturing while maintaining high image quality and wide field of view performance
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 provides wide field of view, high brightness, and high efficiency with reduced weight and complexity, achieving comfortable use and extended viewing times while minimizing glare and image distortions.
Implementation Method 1
an illumination system comprising a spatial light modulator, the illumination system arranged to output light
Implementation Method 2
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 3
an input waveguide arranged to receive light from the transverse anamorphic component; a partially reflective mirror, the input waveguide arranged to guide light from the transverse anamorphic component to the partially reflective mirror along the input waveguide
Implementation Method 4
the partially reflective mirror arranged to reflect at least some of that light
Implementation Method 5
an intermediate waveguide arranged to receive at least some of the light reflected by the partially reflective mirror, the intermediate waveguide arranged to guide the light received from the partially reflective mirror to the lateral anamorphic component along the intermediate waveguide
Implementation Method 6
a lateral anamorphic component having positive optical power in the lateral direction, the intermediate waveguide arranged to guide the light received from the partially reflective mirror to the lateral anamorphic component along the intermediate waveguide
Implementation Method 7
a light reversing reflector that is arranged to reflect light that has been guided along the intermediate waveguide in the first direction so that the reflected light is guided along the intermediate waveguide in a second direction opposite to the first direction to the partially reflective mirror
Implementation Method 8
the partially reflective mirror arranged to transmit at least some of that light
Implementation Method 9
an extraction waveguide arranged to receive at least some of the light transmitted by the partially reflective mirror that has been guided in the second direction along the intermediate waveguide
Implementation Method 10
the extraction waveguide comprises an array of reflective extraction features, the reflective extraction features arranged to extract light guided along the extraction waveguide towards an eye of a viewer
Data Source
AI summary
An anamorphic near-eye display apparatus comprises a spatial light modulator with asymmetric pixels; an input transverse anamorphic lens; an input waveguide that passes input light in a first direction to a partially reflective mirror, an intermediate waveguide comprising a reflective lateral anamorphic component arranged to receive light from the partially reflective mirror and to provide imaging of the spatial light modulator in the lateral direction; and an extraction waveguide arranged to receive light from the reflective lateral anamorphic component. Reflective extraction elements are arranged to extract the imaged light towards the pupil of an observer, maintaining the directionality of the fan of light rays from the spatial light modulator and anamorphic imaging system. A thin, transparent and efficient anamorphic display apparatus for Augmented Reality and Virtual Reality displays is provided.