HMD Eyepiece Waveguide Layout for Stray Light Absorption
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Solution Overview
Problem
Stray light emission in optical imaging systems, such as head-mounted displays, degrades image quality by reducing resolution, contrast, and introducing artifacts.
Innovation Solution
Incorporation of planar waveguides with diffractive optical elements and light absorption assemblies to redirect and absorb stray light using waveguides with higher refractive indices and light-absorbing materials positioned out of the user's field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional eyepieces are used in head-mounted displays, then the device can be compact and immersive, but stray light is emitted from the eyepiece which degrades image quality and causes discomfort
Solution Approach 1:
The patent extracts and removes stray light from the optical path by introducing light absorbers positioned to intercept stray light rays before they reach the user's eye. The light absorbers are integrated into the eyepiece structure at strategic locations where stray light emerges, effectively removing this harmful element without requiring complete redesign of the entire optical system.
Solution Approach 2:
The patent introduces light absorbers as intermediary elements between the waveguide and the user's eye. These absorbers serve as mediators that intercept and absorb stray light rays, preventing them from reaching the user while allowing the main optical function to continue uninterrupted. This intermediary approach adds minimal complexity while effectively addressing the stray light problem.
2Manufacturing precision
If light absorbers are added to reduce stray light, then image quality improves, but manufacturing complexity increases
Solution Approach 1:
The patent implements light absorbers that are nested within or integrated into the existing eyepiece structure. The absorbers are positioned in spaces already present in the optical system, such as within the waveguide structure or between existing optical components. This nesting approach allows stray light control to be added without requiring complete disassembly or complex new mounting structures, thereby improving manufacturing precision while minimizing increases in assembly complexity.
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
Enhances image quality by reducing stray light, increasing resolution, contrast, and accurate color reproduction in optical systems.
Implementation Method 1
one or more first waveguides arranged to receive light from a spatial light modulator at a first edge, guide at least some of the received light to a second edge opposite the first edge
Implementation Method 2
a light absorber positioned to receive stray light exiting the waveguide at the second edge and absorb the received stray light
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
An eyepiece for a head-mounted display includes one or more first waveguides arranged to receive light from a spatial light modulator at a first edge, guide at least some of the received light to a second edge opposite the first edge, and extract at least some of the light through a face of the one or more first waveguides between the first and second edges. The eyepiece also includes a second waveguide positioned to receive light exiting the one or more first waveguides at the second edge and guide the received light to one or more light absorbers.