Crystalline Waveguide for See-Through Near-Eye Display
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Solution Overview
Problem
Conventional AR glasses face challenges in creating large-FOV virtual images with high quality and minimal real-scene image degradation, while maintaining an aesthetically pleasing design and immersive experience.
Innovation Solution
Utilizing a crystalline waveguide with high refractive index materials like bismuth germanium oxide or bismuth silicon oxide, or cubic zirconia, integrated into AR glasses to relay virtual images through total internal reflection, coupled by gratings for diffraction into the user's field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional waveguide materials are used, then manufacturing is easier, but optical quality and transparency are insufficient
Solution Approach 1:
The patent changes the material parameter from conventional waveguide materials to crystalline materials with specific optical properties (high transparency, high refractive index). This parameter change resolves the contradiction by selecting materials that inherently possess both superior optical quality and manageable manufacturing characteristics through established crystal growth techniques.
Solution Approach 2:
The patent employs composite material structures combining crystalline waveguide materials with grating structures. This composite approach enables the waveguide to achieve both high optical quality through the crystalline material and functional performance through the integrated grating, while maintaining manufacturing feasibility through modular fabrication processes.
2Adaptability or versatility
If a prism is suspended in the corner of the user's FOV to deflect light, then the device structure is simpler, but the virtual image is limited to a peripheral location and functionality is reduced
Solution Approach 1:
The patent transitions from a corner-mounted prism (2D peripheral positioning) to a waveguide-based system that distributes virtual images across the entire FOV (2D planar coverage). This dimensional change enables full-field virtual image display while integrating the optical system into the lens structure, reducing overall device complexity.
Solution Approach 2:
The waveguide structure serves multiple functions simultaneously: it acts as the lens of the eyeglasses, relays virtual-image light across the entire FOV, and integrates with grating structures for light coupling. This multi-functionality resolves the contradiction by eliminating the need for separate peripheral prism components while enhancing functional capability.
3Area of stationary object
If the waveguide material has high refractive index, then large-FOV virtual images are enabled, but manufacturing precision requirements increase
Solution Approach 1:
The patent selects crystalline materials with inherently high refractive indices to enable large-FOV virtual images. The high refractive index parameter allows for broader light acceptance angles and larger FOV while the crystalline structure provides natural optical uniformity that mitigates manufacturing precision challenges.
Solution Approach 2:
The patent applies local quality optimization by using crystalline materials with uniform optical properties throughout the waveguide structure. This local uniformity compensates for potential manufacturing variations and maintains high optical quality across the entire large FOV area, reducing the impact of manufacturing precision limitations.
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
Enables large-FOV virtual images with minimal real-scene image dimming and distortion, providing an aesthetically pleasing and immersive AR experience.
Implementation Method 1
Waveguiding is based on total internal reflection. The waveguide material can therefore be transmissive to visible light from the real scene while functioning as a light conduit for visible light from the virtual-image source.
Implementation Method 2
a grating disposed on the waveguide couples the virtual-image-light out of the waveguide toward the user's eye
Data Source
AI summary
A see-through near-eye display device includes an image source configured to emit light conveying an image, a one-dimensional waveguide made of a crystalline material transmissive to visible light and arranged to receive and guide the light emitted by the image source, and a first grating disposed on or in the waveguide. The first grating is configured to couple out of the waveguide at least a portion of the light from the image source after having been guided by the waveguide to the first grating. Several particularly advantageous crystalline waveguide materials are disclosed, which exhibit a high refractive index and high transparency in the visible spectrum. In one class of embodiments, the crystalline waveguide material is based on a bismuth germanium oxide crystal or a bismuth silicon oxide crystal, optionally with substitutions and/or doping. The crystalline waveguide material may be of the form of Bi12Ge1-x-ySixTiyO20, with or without further dopants.