Polymer Eyepiece Stack Alignment Using Diffraction-Guided Stencils
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Solution Overview
Problem
Existing augmented reality systems lack efficient methods for fabricating and assembling multi-layered eyepieces with high precision and alignment, often requiring clean room environments that increase costs and reduce throughput due to contamination risks.
Innovation Solution
An enclosed tool and method for fabricating and assembling multi-layered polymer eyepieces, utilizing a system with integrated stations for casting, curing, coating, aligning, stacking, and edge finishing, which includes a stencil alignment process using optical and diffractive structures for self-aligned assembly, reducing contamination and enhancing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional fabrication methods are used in open environments, then device complexity is reduced, but manufacturing precision deteriorates due to contamination by dust or particles
Solution Approach 1:
The patent combines multiple fabrication stations (casting, curing, coating, aligning, stacking, singulating, and edge finishing) into a single enclosed tool. This integration allows the system to maintain high manufacturing precision through controlled alignment features and fiducial markers while managing device complexity through unified design. The enclosed environment prevents contamination without requiring external clean room facilities.
Solution Approach 2:
The patent introduces fiducial markers and alignment features as intermediary elements between the fabrication process and the final product. These markers serve as reference points that enable precise alignment and positioning throughout the multi-step fabrication process, mediating between the complex tooling system and the eyepiece components being manufactured.
2Manufacturing precision
If clean room environments are used for fabrication, then manufacturing precision is improved, but productivity deteriorates due to restricted access and complex environmental controls
Solution Approach 1:
The patent extracts the clean room requirement from the external environment and relocates it into a self-contained enclosed tool. By integrating the contamination control function directly into the fabrication tool rather than relying on external clean room facilities, the system achieves high manufacturing precision while maintaining unrestricted access and high productivity. The enclosed tool can be positioned anywhere in a standard manufacturing facility.
3Device complexity
If multiple fabrication steps are performed in separate tools, then device complexity is reduced, but loss of time increases due to repeated loading and unloading
Solution Approach 1:
The patent merges seven distinct fabrication steps into a single integrated tool, eliminating the need for repeated loading and unloading between separate tools. This consolidation significantly reduces cycle time and material transfer operations while managing device complexity through unified design. The system performs casting, curing, coating, aligning, stacking, singulating, and edge finishing in one continuous process flow.
Solution Approach 2:
The patent establishes continuous useful action by maintaining the eyepiece components within the enclosed tool throughout the entire fabrication sequence. The components remain in position or are transferred between stations without leaving the controlled environment, eliminating idle time and ensuring continuous productive operation through all fabrication stages.
4Productivity
If an enclosed integrated tool is used, then productivity is improved through synchronized steps, but device complexity increases
Solution Approach 1:
The patent segments the enclosed tool into distinct functional stations (casting, curing, coating, aligning, stacking, singulating, and edge finishing) that operate in sequence. This segmentation allows each station to be optimized for its specific function while contributing to overall productivity through synchronized operation. The modular station design manages device complexity by breaking down the integrated system into manageable functional units.
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
The enclosed tool system enables high-precision, contamination-free fabrication of multi-layered eyepieces with synchronized fabrication and assembly steps, reducing the need for clean room environments and increasing throughput while achieving cost savings.
Implementation Method 1
imaging light diffracted from each incoupling grating
Implementation Method 2
directing light from one or more second light sources to impinge on each of the corresponding diffraction patterns, imaging light diffracted from each incoupling grating
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method of aligning a stencil to an eyepiece wafer includes providing the stencil, positioning the stencil with respect to a first light source, and determining locations of at least two stencil apertures. The method also includes providing the eyepiece wafer. The eyepiece wafer includes at least two eyepiece waveguides, each eyepiece waveguide including an incoupling grating and a corresponding diffraction pattern. The method further includes directing light from one or more second light sources to impinge on each of the corresponding diffraction patterns, imaging light diffracted from each incoupling grating, determining at least two incoupling grating locations, determining offsets between corresponding stencil aperture locations and incoupling grating locations, and aligning the stencil to the eyepiece wafer based on the determined offsets.