Waveguide Anti-Reflection Coating for HMDs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In conventional wearable head-mounted displays (HMDs) for augmented reality, the efficiency of anti-reflective coatings is compromised to maintain see-through performance and display metrics, often sacrificing either the anti-reflective or display performance.
Innovation Solution
The anti-reflection coating is selectively placed in areas outside of the incoupler, outcoupler, and exit pupil expander, allowing for separate optimization of these components and improving the anti-reflective performance without interfering with their functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an anti-reflective coating is applied to the waveguide surface, then the anti-reflective performance is improved, but the see-through performance and display metrics deteriorate
Solution Approach 1:
The patent applies anti-reflective coatings selectively to specific regions of the waveguide surface, specifically areas outside the incoupler, outcoupler, and exit pupil expander regions. This localized application allows the coating to reduce reflections in non-critical areas while leaving the functional optical regions uncoated, thereby maintaining their optical performance characteristics.
Solution Approach 2:
The waveguide surface is divided into multiple functional zones (incoupler region, outcoupler region, exit pupil expander region, and other regions), and the anti-reflective coating is applied only to the non-critical zones. This segmentation allows independent optimization of each region's properties.
2Object-affected harmful factors
If the anti-reflective coating is applied across the entire waveguide surface, then the anti-reflective properties are enhanced, but the grating and coating codesign is compromised
Solution Approach 1:
By applying the anti-reflective coating only to specific regions rather than the entire surface, the patent eliminates the need for complex codesign between gratings and coatings. The functional regions with gratings remain uncoated, allowing independent design and optimization of each component without mutual interference.
Solution Approach 2:
The patent segments the waveguide surface into coated and uncoated regions, separating the anti-reflective function from the grating functions. This reduces design complexity by allowing independent optimization of grating parameters and coating parameters without requiring coordinated codesign.
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 solution enhances the anti-reflective properties of waveguides, improving the visibility and quality of the display while maintaining optimal display metrics and see-through performance.
Implementation Method 1
Once the light beams have been coupled into the waveguide, the light beams are 'guided' through the substrate, typically by multiple instances of total internal reflection (TIR)
Implementation Method 2
an optical coating, such as an anti-reflective coating, is applied to prevent reflection from a lens of the HMD
Data Source
AI summary
A head-mounted display (HMD) system includes a lens element supported by a support structure. The lens element includes a waveguide that includes an incoupler, an outcoupler, and an exit pupil expander. The incoupler is disposed within a first area of the waveguide. The outcoupler is disposed within a second area of the waveguide. The exit pupil expander is disposed within a third area of the waveguide. An anti-reflection coating is formed via fabrication used to form the incoupler, the outcoupler, and the exit pupil expander. The anti-reflection coating is disposed within a fourth area of the waveguide different than the first, second, and third areas of the waveguide.