Waveguide Grating Spatial Phase Variation for Optical Aberrations
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Solution Overview
Problem
Compact planar optical components in wearable display systems, such as waveguides, are prone to optical distortions and aberrations, leading to brightness and color variations in the observed image due to interference between multiple optical paths.
Innovation Solution
An optical waveguide with a diffraction grating that provides a spatial variation of optical phase by meandering grooves or varying fill factor, reducing interference and minimizing brightness and color variations by structuring the grating to diffract the optical beam into a non-zero diffraction order.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If compact planar optical components are used to reduce size and weight, then the weight and size of the optics block are reduced, but optical distortions and aberrations occur leading to brightness and color variations
Solution Approach 1:
The patent applies local quality by introducing a spatially varying phase shift across different regions of the waveguide. The phase shift amount is specifically tailored for different viewing zones to compensate for location-dependent optical path differences, thereby correcting brightness and color variations locally while maintaining the compact planar structure
Solution Approach 2:
The patent changes the optical phase parameter spatially across the waveguide to correct optical aberrations. By modulating the phase of light waves at different positions, the system compensates for interference effects and maintains image quality without increasing the physical size or weight of the optics block
2Volume of moving object
If compact planar optical components are used, then the size of the optics block is reduced, but optical distortions and aberrations occur leading to brightness and color variations
Solution Approach 1:
The patent introduces a spatially varying phase shift across different regions of the waveguide, where each region is optimized for its specific viewing zone. This local optimization corrects brightness and color variations without requiring larger optical components
Solution Approach 2:
The patent addresses optical aberrations by introducing a phase dimension rather than increasing physical dimensions. The phase modulation occurs in the optical wave domain rather than the physical space domain, allowing correction of image quality issues while maintaining compact form factor
3Ease of operation
If a diffraction grating is used to diffract optical beam, then the optical beam is directed into non-zero diffraction order, but interference between multiple optical paths causes brightness and color variations
Solution Approach 1:
The patent converts the harmful interference effects into a beneficial solution by intentionally introducing a controlled phase shift that counteracts the unwanted interference. The phase modulation transforms the problem of optical path interference into an opportunity for active correction, improving brightness uniformity while maintaining effective beam direction control
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 spatial variation of optical phase effectively reduces undesired interference, resulting in improved image quality with minimal brightness and color variations, enhancing the display's performance and user experience.
Implementation Method 1
A first diffraction grating is disposed at the first surface for spreading the optical beam by diffracting portions of the optical beam into a non-zero diffraction order to propagate inside the plate
Implementation Method 2
The first diffraction grating comprises an array of grooves running parallel to one another and structured to provide a spatial variation of optical phase of the portions of the optical beam diffracted by the first diffraction grating into the non-zero diffraction order
Implementation Method 3
a plate of transparent material having opposed first and second surfaces for guiding an optical beam therebetween by at least one of reflection or diffraction
Data Source
AI summary
An optical waveguide is disclosed. The optical waveguide includes a plate of transparent material comprising opposed first and second surfaces for guiding an optical beam between the surfaces by at least one of reflection or diffraction. A diffraction grating is disposed at the first surface for spreading the optical beam by diffracting portions thereof into a non-zero diffraction order to propagate inside the plate. The first diffraction grating includes an array of parallel grooves structured to provide a spatial variation of optical phase of the portions of the optical beam diffracted by the first diffraction grating into the non-zero diffraction order.