Metal-Dielectric Optical Filter With Tapered Edge Protection
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Solution Overview
Problem
Conventional dye-based color filters have broad color passbands and environmental instability, while all-dielectric filters suffer from large center-wavelength shifts and manufacturing challenges, and existing metal-dielectric filters require uniform metal layers for different passbands, limiting design flexibility.
Innovation Solution
A metal-dielectric optical filter design with tapered metal edges protected by dielectric layers, allowing for environmentally durable and flexible optical designs suitable for various sensor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If all-dielectric color filters are used, then transmission levels and color brilliance are improved, but center-wavelength shifts with incidence angle changes increase
Solution Approach 1:
The patent combines metal layers (silver, aluminum, or copper) with dielectric layers to create metal-dielectric optical filters. This composite structure leverages the high transmission properties of dielectric materials while the metal layers provide angle-insensitive optical filtering, resolving the contradiction between transmission level and wavelength stability.
Solution Approach 2:
The patent changes the material parameter from purely dielectric to metal-dielectric composite, and adjusts the structural parameter by controlling metal layer thickness (5-50 nm) and dielectric layer thickness (50-500 nm). These parameter changes enable narrow passbands with minimal wavelength shift while maintaining high transmission.
2Illumination intensity
If all-dielectric color filters are used, then color brilliance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces multiple stacked dielectric layers with a metal-dielectric composite structure. The metal layers (5-50 nm thick) combined with fewer dielectric layers (50-500 nm thick) achieve the same or better color brilliance with reduced structural complexity and manufacturing difficulty.
Solution Approach 2:
The patent introduces metal layers at specific positions within the filter structure to locally enhance optical filtering properties. This localized use of metal materials provides the desired color brilliance without requiring throughout the entire filter structure, reducing overall complexity.
3Ease of manufacture
If metal-dielectric filters with uniform metal layers are used, then manufacturing is simplified, but design flexibility for different passbands is reduced
Solution Approach 1:
The patent allows different metal layer thicknesses (5-50 nm) and compositions (silver, aluminum, copper) at different positions and for different passbands. This localized variation in metal layer properties enables flexible passband design while maintaining relatively simple manufacturing processes for each specific filter type.
Solution Approach 2:
The patent enables design flexibility by allowing variation in metal layer thickness, material composition, and dielectric layer thickness (50-500 nm) to tune different passbands. These parameter changes provide versatile optical filtering capabilities while maintaining a consistent metal-dielectric structural approach that simplifies manufacturing.
4Ease of manufacture
If metal layers are exposed at filter edges, then fabrication is simplified, but environmental durability decreases
Solution Approach 1:
The patent applies dielectric protective layers over the metal layers before the filter is fully assembled. This beforehand protection prevents environmental degradation (oxidation, corrosion) of the metal layers, ensuring long-term reliability while allowing simplified fabrication processes.
Solution Approach 2:
The patent creates a composite structure where dielectric layers encapsulate and protect the metal layers. This composite design combines the manufacturing advantages of exposed metal edges with the environmental durability of protected metal surfaces, as the dielectric layers serve as both structural and protective elements.
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 design provides narrow passbands with minimal wavelength shift and improved environmental resistance, reducing noise from IR and UV leakage and enabling smaller, more durable optical filters for image and UV sensors.
Implementation Method 1
each of the one or more metal layers has a tapered edge, at a periphery of the optical filter, that is protectively covered by at least one of the one or more dielectric layers
Data Source
AI summary
An optical filter, a sensor device including the optical filter, and a method of fabricating the optical filter are provided. The optical filter includes one or more dielectric layers and one or more metal layers stacked in alternation. The metal layers are intrinsically protected by the dielectric layers. In particular, the metal layers have tapered edges that are protectively covered by one or more of the dielectric layers.