Near-Eye Waveguide Facets for Uniform Virtual Image Fidelity
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Solution Overview
Problem
Existing near eye displays (NEDs) face challenges in providing high fidelity virtual images while meeting ergonomic, technical, and financial constraints, requiring a comfortably large eye motion box with clear, relatively high fidelity images without optical artifacts, and being small, lightweight, and energy efficient.
Innovation Solution
The GOODIS system uses partially reflective, dielectric-coated facets in waveguides to expand the input aperture, ensuring uniform light intensity distribution across the field of view by optimizing reflectivity based on polarization and angle of incidence, using a configuration that maintains high fidelity and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a relatively large output aperture is used to fill the eye motion box, then the user can comfortably view virtual images without precise alignment, but the device size and weight increase
Solution Approach 1:
The patent implements nested waveguides where a second waveguide is positioned within or alongside the first waveguide. This nesting arrangement allows multiple light propagation paths to be integrated in a compact volume, achieving a large effective output aperture while minimizing the overall device footprint and weight.
Solution Approach 2:
The patent utilizes three-dimensional waveguide structures with light propagating through multiple dimensions via total internal reflection. By employing waveguides that extend in multiple spatial dimensions and usingfacets oriented at various angles, the system expands the effective output aperture area without proportionally increasing the device's external dimensions.
2Illumination intensity
If multiple facets with different reflectivity coatings are used to expand the aperture, then uniform light intensity distribution is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent applies different dielectric reflectivity coatings to different facets within the waveguide structure. Each facet or group of facets receives a coating optimized for its specific angular range and polarization state, achieving uniform overall light distribution while allowing modular manufacturing of facet assemblies with standardized coating processes.
Solution Approach 2:
The patent varies the dielectric coating parameters (reflectivity, polarization dependence, angular response) across different facets to compensate for variations in light propagation angles and polarization states. This parameter optimization across the facet array achieves uniform intensity distribution while maintaining compatibility with standard dielectric coating technologies.
3Manufacturing precision
If dielectric coatings with polarization-dependent reflectivity are used, then high fidelity image projection is achieved, but sensitivity to polarization variations increases
Solution Approach 1:
The patent divides the waveguide facets into multiple groups, each with dielectric coatings optimized for specific polarization states and angular ranges. By segmenting the facets and assigning appropriate coatings to each segment, the system achieves high overall fidelity while reducing the polarization sensitivity of any individual facet group.
Solution Approach 2:
The patent employs composite dielectric coating structures on the facets that combine multiple layers with different optical properties. These composite coatings are engineered to provide controlled polarization-dependent reflectivity while maintaining broadband performance and reduced sensitivity to polarization variations across the operating range.
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 GOODIS system achieves high fidelity and uniform brightness in the projected virtual images, preserving relative brightness and spatial uniformity to within 30% of the input image, while maintaining a compact and efficient design.
Implementation Method 1
reflects light from the received virtual image from a plurality of partially reflective, optionally dielectric, mirrors, also referred to as facets
Implementation Method 2
Polarization of light received from the display engine and/or reflectivity of a dielectric coating for s and/or p polarized light for at least one facet as a function of incident angle
Implementation Method 3
Each of the LOEs comprises a waveguide having two parallel, totally internally reflecting (TIR) surfaces
Implementation Method 4
Each of the LOEs comprises a waveguide having two parallel, totally internally reflecting (TIR) surfaces and an array of embedded facets
Data Source
AI summary
An image delivery system (IDS) comprising: a first waveguide comprising an input aperture for receiving an input virtual image provided by a display engine and a first plurality of first facets positioned to reflect light from the received input virtual image out from the first waveguide; a second waveguide configured to receive the light reflected out from the first waveguide and comprising a second plurality of second facets positioned to reflect the received light out from the second waveguide to project an output virtual image responsive to the input into an eye motion box (EMB); and a partially reflective coating formed on each facet selected from a number of different partially reflective coatings less than a total number of facets equal to a sum of the number of facets in the first and second pluralities; wherein the output virtual image exhibits a fidelity of 80% or better.