Zinc Chalcogenide Adhesion Layers for Gold IR Mirrors
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Solution Overview
Problem
Existing infrared (IR) and thermal imaging systems face challenges in achieving high reflectance and durability, particularly in the infrared range, due to issues with adhesion layers used in gold mirrors, which affect optical performance and environmental durability.
Innovation Solution
The use of zinc chalcogenide adhesion layers, such as ZnSe or ZnS, to enhance bonding between gold layers and neighboring layers, as well as between the coating stack and the substrate, thereby improving reflectance and durability in IR and thermal imaging applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional adhesion layers are used in gold mirrors, then manufacturing is simpler, but optical performance and environmental durability deteriorate
Solution Approach 1:
A zinc chalcogenide adhesion layer is introduced as an intermediary between the gold reflective layer and the substrate or neighboring dielectric layers. This intermediate layer specifically addresses the poor adhesion of gold to other materials while maintaining high infrared reflectance, thereby improving environmental durability without significantly complicating the overall coating structure.
Solution Approach 2:
The optical coating is designed as a composite structure combining gold (for high reflectance) with zinc chalcogenide (for adhesion and durability). This composite approach leverages the complementary properties of each material: gold provides optical performance while zinc chalcogenide provides mechanical adhesion and environmental stability, resolving the contradiction between simplicity and durability.
2Illumination intensity
If gold layers are used for high reflectance, then optical performance improves, but adhesion to neighboring layers and substrate deteriorates
Solution Approach 1:
The zinc chalcogenide layer serves as a mediator that chemically or physically bonds to both the gold layer and the substrate or dielectric layers. This intermediate adhesion layer enables the gold layer to maintain its high infrared reflectance properties while achieving strong bonding to surrounding structures, thus resolving the adhesion problem without compromising optical performance.
3Reliability
If adhesion layers are added to improve bonding, then durability improves, but manufacturing complexity increases
Solution Approach 1:
The patent specifies optimal thickness ranges for the zinc chalcogenide adhesion layer (typically 5-50 nm) and defines specific material compositions (ZnS, ZnSe, or ZnTe). By establishing precise parameter specifications, the patent enables standardized manufacturing processes that achieve reliable adhesion without requiring complex multi-step fabrication procedures, thus balancing durability with ease of manufacture.
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 implementation of zinc chalcogenide adhesion layers results in optical elements with superior environmental and mechanical durability, achieving high reflectance of greater than or equal to 98% for wavelengths from 7.5 μm to 13.5 μm, while simplifying device design and manufacturing.
Implementation Method 1
The coatings may include one or more adhesion layers of zinc chalcogenide for forming strong bonding between a gold layer and its neighboring layers
Implementation Method 2
The coating may have an average reflectance of greater than or equal to 98%, or greater than or equal to 99%, for all wavelengths from 7.5 μm to 13.5 μm incident on a major surface of the coating
Data Source
AI summary
Optical elements, optical coatings, and methods of making the same are described herein. In some embodiments, an optical element may include a substrate and a coating. The coating may include a first major surface and a second major surface opposite the first major surface, and the first major surface of the coating may be in direct contact with the substrate. The coating may further include a layer of zinc chalcogenide atop the substrate and a layer of Au atop the layer of zinc chalcogenide. In some embodiments, the coating may further include another layer of zinc chalcogenide atop the layer of Au.