See-through Display Optics Stray Light Management
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Solution Overview
Problem
Head-mounted displays (HMDs) with see-through capabilities suffer from stray light issues, which reduce image sharpness and contrast by causing black areas to appear gray, affecting the quality of both the displayed image and the see-through view of the environment.
Innovation Solution
The implementation of an upper optical module with a DLP display, polarized light source, reflective polarizer, and a light trap to manage stray light by directing dark state light away from the optical axis, using a TIR wedge and corrective wedge to maintain image light quality and absorb stray light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a see-through display system is used to provide environmental visibility, then the see-through view is achieved, but stray light scatters and reduces image sharpness and contrast
Solution Approach 1:
The patent extracts and removes stray light from the optical system using dedicated light trapping structures. These structures are positioned to intercept and absorb scattered light paths, separating the harmful stray light from the useful image light, thereby resolving the contradiction between see-through capability and image quality
Solution Approach 2:
The patent introduces intermediary optical elements including polarizing filters, wave plates, and light trapping structures that mediate between the light source and the user's eye. These intermediaries selectively manage light paths to maintain both see-through functionality and image sharpness by controlling which light reaches the user
2Illumination intensity
If stray light is present in the optics, then the see-through view is maintained, but black areas appear gray and contrast is reduced
Solution Approach 1:
The patent applies local quality by creating different optical properties in different regions of the optical system. Light trapping structures with specific absorptive properties are positioned in regions where stray light is most problematic, while maintaining high transmittance in regions where see-through view is critical. This localized approach allows simultaneous optimization of black level and see-through brightness
Solution Approach 2:
The patent converts the harmful effect of stray light into a beneficial outcome by using the scattered light to illuminate and reveal internal optical structures, which are then deliberately designed to trap and absorb this light. The stray light that would normally degrade image quality is instead used to illuminate the optical path and then captured by strategically placed light traps, improving both contrast and see-through performance
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
This configuration achieves high contrast, deep blacks, and reduced stray light, resulting in sharper and more immersive see-through displays with improved image quality.
Implementation Method 1
polarized light source
Implementation Method 2
reflective polarizer
Implementation Method 3
TIR wedge
Implementation Method 4
corrective wedge
Implementation Method 5
light trap to manage stray light
Data Source
AI summary
Aspects of the present invention relate to providing see-through computer display optics.