Light-Guide Optical Element Layout for Near-Eye Chromatic Control
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Solution Overview
Problem
Compact near-eye display systems face design challenges due to stringent waveguide geometry requirements that conflict with aesthetic and angular orientation preferences for the image projector, leading to unfavorable projector positioning and potential chromatic aberrations.
Innovation Solution
A light-guide optical element (LOE) with progressive deflection arrangements and a reflective coupling-in surface obliquely oriented to both X and Y axes, combined with a transparent wedge element to correct chromatic aberrations, allows for flexible projector integration and minimizes chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the projector is integrated to conform aesthetically to the waveguide geometry, then the aesthetic appearance is improved, but the projector orientation becomes unfavorable and chromatic aberrations occur
Solution Approach 1:
A reflective coupling-in surface is introduced as an intermediary component between the projector and the waveguide. This surface obliquely couples light from the projector into the waveguide, allowing the projector to be positioned at an aesthetically pleasing orientation while still achieving proper light coupling and minimizing chromatic aberrations
Solution Approach 2:
The reflective coupling-in surface is obliquely oriented to both the X axis and the Y axis, utilizing three-dimensional spatial orientation to resolve the conflict between aesthetic projector positioning and optimal optical coupling. This allows the projector to be positioned outside the conventional planar alignment with the waveguide
2Reliability
If the projector is positioned to meet waveguide orientation requirements, then optical performance is improved, but the aesthetic appearance deteriorates
Solution Approach 1:
The reflective coupling-in surface serves as a mediator that decouples the projector positioning from the waveguide orientation requirements. It allows the projector to be positioned for aesthetic purposes while still achieving the necessary optical coupling angle for optimal performance
3Device complexity
If a conventional coupling arrangement is used, then the structure is simple, but chromatic aberrations occur
Solution Approach 1:
The reflective coupling-in surface acts as an intermediary optical element that corrects chromatic aberrations by properly managing the light coupling angle. While it adds a component to the system, it maintains structural simplicity compared to more complex optical correction systems
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 enables aesthetically pleasing projector integration and reduces chromatic aberrations, providing a compact and efficient near-eye display with improved image quality.
Implementation Method 1
propagate in a first direction within the LOE by internal reflection at the major external surfaces
Implementation Method 2
redirected by the first progressive deflection arrangement so as to propagate in a second direction within the LOE by internal reflection
Data Source
AI summary
A display (10) includes a flat light-guide optical element (LOE) (100) having first and second progressive deflection arrangements associated with first and second regions (110, 120) of the LOE. A support arrangement (106), such as a glasses frame, supports the LOE in facing relation to the eye of the user. An image projector (200) injects a collimated image into the LOE via a reflective coupling-in surface (131). The reflective coupling-in surface is preferably obliquely oriented to both the major horizontal and vertical axes of the LOE. A multi-component wedge (132) is preferably used to compensate for chromatic aberration.