Wedge Waveguide Illumination for HMD Uniformity
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Solution Overview
Problem
Conventional head-mounted display devices are bulky and heavy, and they often suffer from non-uniform illumination, which affects the quality of virtual and augmented reality experiences.
Innovation Solution
The use of a wedge waveguide optical element that receives illumination light from a light source and propagates it via total internal reflection, providing uniform illumination to a spatial light modulator, which enhances image quality and reduces device size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional illuminators are used in head-mounted display devices, then the device can provide illumination to the spatial light modulator, but the device becomes bulky and heavy
Solution Approach 1:
The patent combines the illumination path and display optical path into a single wedge waveguide structure. The illuminator optics are integrated within the waveguide itself, eliminating the need for separate illuminator components and reducing overall device complexity and weight while maintaining effective illumination of the spatial light modulator
Solution Approach 2:
The illumination optical elements are nested within the wedge waveguide structure. The waveguide serves dual purposes as both the illumination delivery mechanism and the display optical element, with illumination optics positioned within the waveguide body, thereby reducing the number of discrete components and overall device size
2Manufacturing precision
If conventional illuminators are used in head-mounted display devices, then the device can provide illumination to the spatial light modulator, but the illumination is non-uniform which affects image quality
Solution Approach 1:
The wedge waveguide features non-parallel surfaces with different angles that create localized variations in light propagation paths. This geometric configuration ensures that illumination light is distributed more uniformly across the spatial light modulator surface, addressing the non-uniform illumination problem while maintaining a relatively simple optical element structure
Solution Approach 2:
The waveguide employs asymmetric non-parallel surfaces rather than symmetric parallel plates. This asymmetric geometry creates diverse light propagation angles and paths that promote more uniform light distribution across the output surface, improving illumination uniformity without requiring complex additional optical components
3Manufacturing precision
If a wedge waveguide with non-parallel surfaces is used, then uniform illumination is achieved, but the optical path becomes more complex
Solution Approach 1:
The wedge waveguide structure performs multiple functions simultaneously: it serves as the illumination delivery mechanism, the optical path guidance structure, and the uniforming element for light distribution. The integrated design eliminates the need for separate components to achieve each function, reducing overall device complexity despite the non-parallel surface geometry
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 solution results in lightweight, compact head-mounted display devices that offer high-quality, uniform illumination for improved virtual and augmented reality experiences.
Implementation Method 1
The optical element is configured to receive the illumination light provided by the light source at the first surface, propagate the illumination light via total internal reflection, and output the illumination light
Data Source
AI summary
A device for illuminating a spatial light modulator includes a light source and an optical element. The light source is configured to provide illumination light. The optical element has a first surface, a second surface that is distinct from and non-parallel to the first surface, and a third surface that is distinct from and non-parallel to the first surface and the second surface. The optical element is configured to receive the illumination light at the first surface, propagate the illumination light via total internal reflection, and output the illumination light from the third surface. Also disclosed is a method performed by the device.