Wire Grid Polarizer Oxidation Barrier Coatings
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Solution Overview
Problem
Wire grid polarizers (WGPs) face degradation due to oxidation, corrosion, and mechanical damage, leading to reduced performance and contrast, especially in extreme environments, and existing protective coatings may adversely affect their performance.
Innovation Solution
A WGP with a conformal-coating that includes a barrier layer of aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, hafnium oxide, or zirconium oxide, applied via vapor deposition, providing protection against oxidation, corrosion, and mechanical damage while minimizing performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective coatings are applied by dipping the WGP in an aqueous solution, then the coating adheres to the ribs, but the coating may be insufficient for WGP protection in extreme environments and can adversely affect polarizer performance
Solution Approach 1:
The patent changes the deposition method from aqueous solution dipping to vapor deposition, and changes the coating composition to specific materials (aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, hafnium oxide, zirconium oxide, or rare earth oxides). This parameter change enables sufficient protection in extreme environments while minimizing performance degradation by forming dense, adherent coatings without excessive thickness.
Solution Approach 2:
The patent specifies using compounds of aluminum, silicon, hafnium, zirconium, or rare earth elements as protective coating materials. These composite material choices provide both excellent protection against oxidation and corrosion in extreme environments and maintain optical performance by being available in controlled, thin layers through vapor deposition.
2Reliability
If thicker coatings are applied to provide sufficient oxidation or corrosion protection, then protection effectiveness increases, but polarizer performance degradation increases
Solution Approach 1:
The patent changes the deposition method to vapor deposition, which enables formation of sufficient protective coatings at much thinner thicknesses compared to aqueous solution methods. This parameter change resolves the contradiction by providing adequate oxidation and corrosion protection while minimizing impact on light transmission efficiency.
Solution Approach 2:
The patent employs thin film protective coatings deposited by vapor deposition. These thin films provide sufficient protection against oxidation and corrosion while being thin enough to minimize performance degradation, effectively resolving the contradiction between protection thickness and optical performance.
3Reliability
If water condenses onto the WGP and wicks into narrow channels between ribs, then corrosion occurs, but the capillary action makes protection difficult
Solution Approach 1:
The patent applies thin film protective coatings conformally deposited on the ribs. These thin films create a continuous barrier that prevents water from wicking into the narrow channels between ribs through capillary action, while the conformal deposition ensures complete coverage even in difficult-to-reach areas.
Solution Approach 2:
The patent changes from aqueous solution coating to vapor deposition, which produces denser, more impermeable coatings that effectively block water ingress. This parameter change provides superior corrosion resistance by preventing water from penetrating into the narrow channels where it would cause corrosion.
4Reliability
If aluminum ribs form natural oxide over time, then oxidation protection occurs, but the underlying aluminum is consumed, reducing wire size and changing polarization characteristics
Solution Approach 1:
The patent applies a protective coating by vapor deposition before the aluminum ribs have a chance to form natural oxide. This preliminary action prevents the consumption of underlying aluminum through natural oxidation, thereby maintaining the original wire size and polarization characteristics while still providing oxidation protection.
Solution Approach 2:
The patent uses compounds of aluminum, silicon, hafnium, zirconium, or rare earth elements as protective coatings. These materials provide oxidation protection without consuming the underlying aluminum ribs, thus preserving the precise dimensions and polarization characteristics required for optimal performance.
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 conformal-coating effectively protects the ribs from oxidation and corrosion, maintaining high contrast and transmission efficiency, and reduces the risk of mechanical damage, thereby enhancing the long-term performance of WGPs in various applications.
Implementation Method 1
A conformal-coating that includes a barrier layer of aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, hafnium oxide, or zirconium oxide, applied via vapor deposition
Data Source
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AI summary
A wire grid polarizer (WGP) (10) can have a conformal-coating (13) to protect the WGP (10) from oxidation and/or corrosion. The conformal-coating (13) can include a barrier layer with at least one: of aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, hafnium oxide, and zirconium oxide. A method of making a WGP (10) can include applying the barrier layer over ribs (12) of a WGP (10) by vapor deposition.