Multilayer Diffractive Optical Elements for Display Headsets
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Solution Overview
Problem
Conventional diffractive optical elements (DOEs) used in display headsets for virtual and augmented reality cause ghosting, glare, and optical aberrations like chromatic aberration, spherical aberration, coma, astigmatism, and field curvature, obscuring images due to diffraction and scattering of light.
Innovation Solution
A display headset design incorporating a dual diffractive optical element structure with protective layers made of resin, where each diffractive optical element has ridges and corresponding protective layers with similar ridges, and a lens, to enhance diffraction efficiency and correct optical errors, reducing scattering and diffraction across various wavelengths and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional diffractive optical element is used to enhance diffraction efficiency, then the diffraction efficiency is improved, but optical aberrations such as chromatic aberration, spherical aberration, coma, astigmatism, and field curvature occur
Solution Approach 1:
The patent divides the single diffractive optical element into multiple separate diffractive optical elements (first DOE, second DOE, third DOE) positioned at different locations in the optical path. Each element has specific ridge structures designed to address particular optical aberrations, allowing the system to achieve high diffraction efficiency while correcting chromatic aberration, spherical aberration, and other optical distortions through the combined effect of segmented elements.
2Adaptability or versatility
If a diffractive optical element is placed near the eyes to present images, then the field of view is enhanced, but ghosting and glare occur due to diffraction and scattering of light
Solution Approach 1:
The patent introduces protective layers as intermediary elements between the diffractive optical elements and the external environment. These protective layers serve multiple functions: they protect the delicate ridge structures of the DOEs from damage while maintaining optical transparency, reduce surface scattering that causes ghosting and glare, and enable the system to achieve wide field of view without the harmful optical artifacts associated with conventional DOEs.
3Loss of energy
If ridges are added to diffractive optical elements to enhance diffraction efficiency, then the diffraction efficiency is improved, but the device complexity increases
Solution Approach 1:
Instead of creating a single complex diffractive element with all necessary ridge structures, the patent segments the functionality across multiple simpler diffractive elements. Each element has a manageable number of ridges with specific geometries optimized for particular wavelength ranges or optical corrections, making individual fabrication easier while achieving cumulative high diffraction efficiency through the combination of segmented elements in the optical path.
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 effectively minimizes optical aberrations and enhances image transmission efficiency, providing clear and undistorted images over a wide field of view, improving the overall virtual and augmented reality experience by compensating for diffraction efficiency variations.
Implementation Method 1
a diffractive optical element (DOE) may be placed between human eyes and the display device to enhance the diffraction efficiency
Implementation Method 2
The first protective layer and the second protective layer compensate for a variation in a diffraction efficiency at different wavelengths and incident angles of the image light
Data Source
AI summary
The display headset for presenting an image to a user includes an electronic display and an optics block. The electronic display emits image light associated with the image toward an exit pupil corresponding to a location of an eye of the user. The optics block directs the image light from the electronic display to the exit pupil. The optics block includes a first diffractive optical element between the exit pupil and the electronic display, a second diffractive optical element between the first diffractive optical element and the exit pupil, a first protective layer on the first diffractive optical element to protect the first diffractive optical element, and a second protective layer on the second diffractive optical element to protect the second diffractive optical element. The first protective layer and the second protective layer compensate for a variation in a diffraction efficiency at different wavelengths and incident angles of the light.