Multi-phase infrared ceramic with matched refractive indices
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Solution Overview
Problem
Ceramic materials used in optical windows for projectiles and sensors often lack structural integrity and suffer from refractive index mismatches between phases, leading to opacity and reduced transmissivity in the infrared spectrum due to significant differences in refractive indices.
Innovation Solution
A co-doped ceramic material with two phases, where each phase is doped to minimize refractive index differences, allowing for improved infrared light transmission by homogeneously mixing dopants within the ceramic phases, thereby reducing scatter and enhancing in-line transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple ceramic materials are used to form a multi-phase ceramic, then the structural integrity and resistance to extreme forces/temperatures is improved, but the refractive index mismatch between phases causes reduced infrared transmissivity
Solution Approach 1:
The patent applies parameter changes by systematically adjusting the dopant concentrations in each ceramic phase to achieve refractive index matching. Specifically, the first dopant concentration is optimized to increase the refractive index of the first ceramic phase, while the second dopant concentration is optimized to decrease the refractive index of the second ceramic phase, bringing both phases to a common refractive index value and enabling high infrared transmissivity while maintaining structural integrity
Solution Approach 2:
The patent employs composite materials by creating a multi-phase ceramic composite where different ceramic phases are combined with specific dopants. The composite structure integrates multiple ceramic materials (such as alumina, magnesia, zirconia) with controlled dopant distributions, allowing the material to simultaneously exhibit the structural strength of ceramics and the optical transparency required for infrared applications
2Reliability
If dopants are added to adjust refractive indices, then the refractive index matching between phases is improved, but the complexity of material composition and manufacturing increases
Solution Approach 1:
The patent manages complexity by focusing on controlling only two key parameters: the type and concentration of dopants in each phase. By establishing specific concentration ranges for the first dopant in the first ceramic phase and the second dopant in the second ceramic phase, the patent provides a systematic approach to achieving refractive index matching without requiring complex multi-component compositions or intricate manufacturing processes
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 achieves high infrared light transmissivity and reduced absorbance, enabling the use of ceramic materials in harsh environments with improved structural integrity and spectral transmission across the infrared spectrum.
Implementation Method 1
the first dopant increases the refractive index of the first ceramic material, relative to a refractive index of a corresponding first ceramic material that is free of the first dopant and the second dopant decreases the refractive index of the second ceramic material
Implementation Method 2
mismatches in the refractive index of each material can affect the transmissivity and emittance of the ceramic material
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3
AI summary
Various embodiments disclosed relate to an optical window including an infrared light transmissive optical material. The optical material includes a first ceramic phase including a first ceramic material and a first dopant distributed therein. The optical material further includes a second ceramic phase homogenously intermixed with the first ceramic phase and comprising a second ceramic material and a second dopant distributed therein. The first dopant increases the refractive index of the first ceramic material and the second dopant decreases the refractive index of the second ceramic material. The first dopant and the second dopant are present in an amount such that a difference in a refractive index of the first ceramic phase and of the second ceramic phase is in a range of from about 0.001 to about 0.2.