See-through Display Optics Stray Light Management
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Solution Overview
Problem
Head-mounted displays (HMDs) that provide a see-through view are affected by stray light, leading to reduced image sharpness and contrast, as well as grayish black areas, due to scattered or reflected light within the optics, which compromises the see-through view by combining environmental light with displayed image light.
Innovation Solution
The implementation of optical configurations and light management techniques, such as polarized light sources, reflective polarizers, TIR wedges, and dark light traps, to direct and absorb stray light, ensuring that only intended light reaches the user's eyes, maintaining high contrast and sharpness in the displayed images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light management techniques such as polarized light sources, reflective polarizers, TIR wedges, and dark light traps are implemented, then stray light is reduced and image sharpness and contrast are enhanced, but device complexity increases
Solution Approach 1:
The optical system is divided into multiple functional components: polarized light sources, reflective polarizers, TIR (Total Internal Reflection) wedges, and dark light traps. Each component addresses a specific aspect of stray light management, allowing the system to reduce stray light effectively while maintaining modularity in the optical design
Solution Approach 2:
Different regions of the optical system are treated with specialized light management techniques. For example, specific surfaces are equipped with TIR wedges to redirect stray light, while dark light traps are positioned in areas where scattered light accumulates. This localized approach optimizes stray light reduction without requiring uniform complexity throughout the entire system
2Manufacturing precision
If light management techniques such as polarized light sources, reflective polarizers, TIR wedges, and dark light traps are implemented, then stray light is reduced and contrast is enhanced, but device complexity increases
Solution Approach 1:
The system converts potentially harmful stray light into beneficial effects by using reflective polarizers and TIR wedges to redirect scattered light into dark light traps. This approach transforms the problematic scattered light into a controlled element that enhances image contrast by preventing it from reaching the user's eyes
Solution Approach 2:
Reflective polarizers serve as intermediaries between the light source and the display optics, selectively filtering polarized components of light. These polarizers mediate the light path by allowing desired light to pass while redirecting stray light components, thereby enhancing contrast without requiring complete optical isolation
3Manufacturing precision
If optical configurations and light management techniques are implemented to direct and absorb stray light, then sharpness and contrast are maintained, but loss of energy increases
Solution Approach 1:
The system replaces absorptive light management with reflective and refractive mechanisms. TIR wedges use total internal reflection to redirect stray light without absorption, and reflective polarizers use reflection rather than absorption to filter light. This substitution minimizes energy loss while maintaining sharpness by preserving more light energy in the useful optical path
4Manufacturing precision
If optical configurations and light management techniques are implemented to direct and absorb stray light, then contrast is maintained, but loss of energy increases
Solution Approach 1:
The system converts potentially harmful stray light into beneficial effects by using reflective polarizers and TIR wedges to redirect scattered light into dark light traps. This approach transforms the problematic scattered light into a controlled element that enhances image contrast by preventing it from reaching the user's eyes
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
These solutions effectively reduce stray light, enhancing the sharpness and contrast of displayed images while maintaining a clear see-through view of the environment, providing deep blacks and high brightness, even in complex optical systems like HMDs.
Implementation Method 1
polarized light sources
Implementation Method 2
reflective polarizers
Implementation Method 3
TIR wedges
Implementation Method 4
dark light traps to direct and absorb stray light
Data Source
AI summary
Aspects of the present invention relate to providing see-through computer display optics.