Area-Specific Color Absorption in Waveguide Stacks
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Solution Overview
Problem
Conventional optical waveguide stack architectures struggle with gap control for RGB waveguide stacks, leading to image ghosts and reduced optical sharpness in virtual and augmented reality applications.
Innovation Solution
The use of inkjet-based dye or pigment nanoimprint lithography to create area-specific color-absorbing imprintable layers over various substrates, allowing for precise control over film thickness and absorption of specific wavelengths of light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical waveguide stack architectures are used, then the basic waveguide structure is maintained, but gap control for RGB waveguide stacks is poor leading to image ghosts and reduced optical sharpness
Solution Approach 1:
The patent applies local quality by creating area-specific color-absorbing regions within the waveguide structure. Different regions of the waveguide are selectively treated with color-absorbing materials that have specific wavelength absorption properties, allowing precise control over light propagation in different areas. This local differentiation enables better gap control and eliminates image ghosts by absorbing stray light in specific regions while maintaining transparency in others.
Solution Approach 2:
The patent utilizes color changes by incorporating color-absorbing materials that selectively absorb specific wavelengths of light. These materials are applied in controlled patterns to the waveguide, creating regions with different optical absorption characteristics. The color-absorbing properties are precisely engineered to match the RGB wavelength ranges, enabling selective absorption of unwanted light while maintaining the desired optical properties for image projection.
2Reliability
If area-specific color-absorbing layers are added to improve light absorption control, then image sharpness improves, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated layer. The color-absorbing imprintable layer simultaneously serves as both the structural waveguide component and the optical filtering element. By combining the waveguide function with the color absorption function in one layer, the patent avoids adding separate complex subsystems while achieving improved image sharpness through selective wavelength absorption.
Solution Approach 2:
The imprintable layer is designed with multi-functionality, serving as both a structural component of the waveguide and an optical filter for color absorption. This universal layer performs multiple roles: guiding light, absorbing stray light in specific wavelength ranges, and maintaining the waveguide's structural integrity. The inkjet-based fabrication method also provides universal applicability across different waveguide configurations.
3Manufacturing precision
If inkjet-based dye or pigment nanoimprint lithography is used for precise film thickness control, then manufacturing precision improves, but ease of manufacture decreases
Solution Approach 1:
The patent replaces conventional mechanical lithography methods with inkjet-based deposition. Instead of using mechanical contact and pressure to create patterns, the inkjet system uses non-contact droplet ejection to deposit color-absorbing materials with precise spatial control. This substitution eliminates the complexity of mechanical alignment and contact-based patterning while achieving superior film thickness control and area-specific application.
Solution Approach 2:
The patent utilizes parameter changes in the inkjet deposition process to achieve precise film thickness control. By adjusting inkjet parameters such as droplet volume, deposition speed, and number of passes, the film thickness can be precisely controlled in different regions. The UV curing process parameters are also optimized to achieve complete polymerization while maintaining the desired film properties, enabling precise control without complicating the overall manufacturing approach.
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 approach enhances the flexibility of waveguide stack designs, reduces the wearable form factor of waveguides, and improves image sharpness by absorbing stray light and preventing unwanted light propagation.
Implementation Method 1
the color-absorbing region is configured to absorb a component of the visible light as the visible light propagates through the optical waveguide
Implementation Method 2
the transmissive input coupler is configured to couple incident visible light to the optical waveguide
Implementation Method 3
make the waveguide stack architecture more flexible to designs, for example, in the use of inline single pupil input coupling gratings (ICGs) or split pupil ICGs where pupil positioning can overlap fully or partially over different substrates in the stack. This allows absorption of stray light entering a specific color waveguide where it does not propagate through and cause undesirable optical image quality
Data Source
AI summary
An eyepiece includes an optical waveguide, a transmissive input coupler at a first end of the optical waveguide, an output coupler at a second end of the optical waveguide, and a polymeric color absorbing region along a portion of the optical waveguide between the transmissive input coupler and the output coupler. The transmissive input coupler is configured to couple incident visible light to the optical waveguide, and the color-absorbing region is configured to absorb a component of the visible light as the visible light propagates through the optical waveguide.