See-Through Maxwellian Waveguide Display With PMHOE Eyebox Expansion
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Solution Overview
Problem
Conventional waveguide-type augmented reality near-eye displays suffer from vergence-accommodation conflict (VAC) and have a restricted eyebox due to the use of thick waveguides and limited exit pupil expansion techniques, leading to user discomfort and impaired immersive experience.
Innovation Solution
A waveguide-type see-through Maxwellian near-eye display utilizing a pin-mirror holographic optical element (PMHOE) array is employed, which includes a waveguide and a PMHOE array to diffract light towards the user, maintaining a thin form factor while enlarging the eyebox and providing a deep depth of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional waveguide-type AR NED uses a single virtual image plane based on a collimated display engine, then the optical structure is simplified, but the vergence-accommodation conflict (VAC) problem occurs causing user visual discomfort
Solution Approach 1:
The patent segments the single virtual image plane into multiple virtual image planes at different depths. The display system presents multiple images corresponding to different focal distances, allowing the user's eye to accommodate at different depths while maintaining vergence alignment, thereby resolving the VAC problem without significantly complicating the optical structure
Solution Approach 2:
The patent changes the focal distance parameter of the virtual images by presenting images at multiple different depths. This parameter change allows the accommodation distance to match the vergence distance for each image plane, eliminating visual discomfort while maintaining a relatively simple optical structure
2Adaptability or versatility
If a conventional AR NED uses an optical combiner to enable see-through capability, then virtual image superimposition is achieved, but the optical structure becomes more complicated than VR NED
Solution Approach 1:
The patent uses a waveguide as an intermediary optical element that enables see-through capability without requiring a traditional optical combiner. The waveguide couples light from the display engine into the user's eye while allowing ambient light to pass through, achieving virtual image superimposition with a simpler optical structure
Solution Approach 2:
The patent replaces the mechanical optical combiner system with a waveguide-based optical system. The waveguide uses total internal reflection and diffraction grating to guide and couple light, substituting the need for a physical combiner and simplifying the overall optical structure while maintaining see-through capability
3Illumination intensity
If a conventional AR WNED uses diffraction grating-based components for in/out-couplers, then high optical transparency is achieved, but the eyebox remains small requiring exit pupil expansion techniques
Solution Approach 1:
The patent extends the eyebox in the lateral dimension by using multiple diffraction grating-based out-couplers arranged in an array. Each out-coupler serves a specific angular range, and their collective arrangement expands the overall eyebox area while maintaining high optical transparency through the diffraction grating mechanism
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 PMHOE array effectively mitigates VAC by allowing clear virtual image observation across various focal distances and enlarges the eyebox, enhancing user comfort and tolerance, while maintaining a compact form factor.
Implementation Method 1
a pin-mirror holographic optical element (PMHOE) array configured to attach to the waveguide and to diffract light propagated within the waveguide toward a user
Data Source
AI summary
Various embodiments provide a waveguide-type see-through Maxwellian near-to eye display having an eyebox enlarged using a pin mirror holographic optical element array. According to various embodiments, the waveguide-type see-through Maxwellian near-to-eye display comprises: a waveguide; and a pin mirror holographic optical element array which is attached to the waveguide and diffracts light propagating within the waveguide toward a user.