Gradient Thickness Coating for Homogeneous Waveguide Emission
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Solution Overview
Problem
Existing waveguide coatings result in non-homogeneous emission, leading to variability in brightness and spectral performance, particularly when waveguiding light with multiple wavelengths, and are complex and costly to manufacture.
Innovation Solution
A waveguide with a first surface featuring a graded coating of alternating dielectric layers with controlled thickness changes, optimized for specific wavelengths, allowing for homogeneous emission and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional waveguide coatings are used, then manufacturing is simpler, but emission homogeneity and spectral performance deteriorate
Solution Approach 1:
The coating is divided into multiple alternating dielectric layers (first dielectric material and second dielectric material) with different refractive indices. Each layer has a specific thickness (50-200 nm) that contributes to the overall gradient structure, enabling precise control of optical properties while maintaining manufacturability through standardized layer deposition processes.
Solution Approach 2:
The coating thickness varies locally across the waveguide surface, creating a gradient from thicker regions to thinner regions. This local variation in thickness (controlled through shadow mask geometry) allows different regions of the waveguide to have optimized optical properties for their specific function, achieving homogeneous emission while managing complexity through localized rather than global changes.
2Adaptability or versatility
If gradient thickness coating is applied to optimize spectral performance, then wavelength-specific emission improves, but manufacturing complexity increases
Solution Approach 1:
The coating design utilizes systematic parameter variations including layer thickness (50-200 nm), refractive index differences between alternating layers, and gradient thickness profiles. These parameter changes are optimized for specific wavelength ranges, allowing the same manufacturing process to produce coatings tailored to different spectral requirements by adjusting deposition parameters rather than changing the fundamental coating approach.
Solution Approach 2:
The coating employs composite structures with alternating dielectric materials having different refractive indices. This composite approach enables enhanced spectral control through interference effects while maintaining compatibility with existing vacuum deposition manufacturing processes. The composite nature allows tuning of optical properties by selecting different material combinations without fundamentally changing the manufacturing method.
3Manufacturing precision
If multiple coating layers with varying thickness are deposited, then emission homogeneity improves, but manufacturing time and cost increase
Solution Approach 1:
The multi-layer coating structure segments the optical control function into discrete layers, each contributing to the overall emission homogeneity. By using a limited number of alternating dielectric layers with standardized thickness ranges (50-200 nm), the design achieves precision without requiring excessive layer counts, thus balancing manufacturing time with performance.
Solution Approach 2:
The shadow mask is designed with predetermined geometry that establishes the gradient thickness profile during the initial coating deposition. This preliminary structuring of the coating process through mask design eliminates the need for subsequent complex thickness adjustments or multiple iterative deposition cycles, thereby improving productivity while maintaining emission homogeneity.
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 solution provides spatially homogeneous emission across replicas, improving image quality and reducing manufacturing complexity and cost.
Implementation Method 1
a shadow mask arranged (i.e. shaped and/or positioned) such that a first target provides a first coating contribution and the second target provides a second coating contribution
Implementation Method 2
a source of coating material, each target providing a respective coating contribution
Data Source
AI summary
A coating device comprising a sample carrier, a source, shadow mask and coating driver. The source comprises a plurality of targets such as a first target and second target. The source is arranged to coat at least one sample housed in the sample carrier. The shadow mask is disposed in a line-of-sight between the sample carrier and source. The shadow mask is arranged such that the first target provides a first coating contribution. The shadow mask is further arranged such that the second target provides a second coating contribution. The second coating contribution is different to the first coating contribution. At least one of the first and second coating contributions is non-uniform in a first dimension of the sample. The coating driver is arranged to independently control the first coating contribution and second coating contribution such that a thickness gradient of the coating in the first direction is variable.