Thin-layer getter for vacuum infrared detectors
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Solution Overview
Problem
Conventional getter configurations for vacuum devices, particularly infrared detectors, require large sizes and high activation temperatures, leading to increased envelope sizes and additional out-gassing, which complicates the removal of hydrogen and other contaminants, limiting detector lifetime and efficiency.
Innovation Solution
A thin-layer laminate comprising a platinum group metal layer, such as palladium oxide, combined with a porous hydrophilic layer of active metal and metal oxide, deposited on a substrate like aluminum or titanium, which absorbs hydrogen and water vapor, and also functions as an IR radiation absorber, eliminating the need for separate getter devices and high activation temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional non-evaporable chemically-active getter is mounted on the outer wall and activated by heating to high temperature, then residual gas molecules are effectively removed from the vacuum space, but the detector elements are damaged by the high activation temperature and the dewar envelope size increases
Solution Approach 1:
The patent changes the activation temperature parameter from high temperature (conventional getters require heating to high temperature for activation) to low temperature (the thin-layer laminate can be activated by simple heating without high temperature damage). This is achieved by using a thin-layer structure with platinum group metals and porous hydrophilic layers that enable effective gettering at lower temperatures, thus protecting detector elements from thermal damage while maintaining vacuum quality
Solution Approach 2:
The patent employs a thin-layer laminate structure deposited on the inner wall surface, replacing the conventional bulky getter mounted on the outer wall. This thin-film approach reduces the spacing requirements between the getter and detector elements, eliminates the need for large dewar envelopes, and enables integration with the cold finger structure without compromising gettering effectiveness
2Reliability
If a conventional getter is mounted on the outer wall, then gas molecules are removed from the vacuum space, but the dewar envelope size increases and unconventional envelope designs are required
Solution Approach 1:
The patent merges the getter function with the inner wall structure of the dewar envelope. The thin-layer laminate is deposited directly on the inner wall surface, combining the structural function of the wall with the gettering function. This integration eliminates the need for separate getter components and reduces the overall dewar envelope volume, allowing for more compact and conventional envelope designs
Solution Approach 2:
The patent uses a thin-layer laminate structure that can be deposited as a thin film on the inner wall, replacing the conventional thick getter material mounted on the outer wall. This thin-film approach significantly reduces the space required for gettering, enabling smaller dewar envelopes and more compact detector designs without compromising vacuum quality
3Reliability
If the inner wall is cooled to low temperature for efficient IR detection, then detector performance is improved, but internal out-gassing occurs and dew forms on the infrared window
Solution Approach 1:
The patent applies preliminary action by depositing the thin-layer laminate getter on the inner wall before the detector is sealed and operated. This pre-installed getter is ready to immediately capture out-gassed molecules as they are released, preventing their accumulation and subsequent condensation as dew on the infrared window. The getter is positioned to intercept gas molecules before they can reach the cold infrared window surface
Solution Approach 2:
The thin-layer laminate acts as an intermediary between the out-gassing sources and the cold infrared window. It captures and immobilizes out-gassed molecules through adsorption and chemisorption, serving as a barrier that prevents these molecules from reaching the cold surfaces where they would condense as dew, thus protecting the infrared window while allowing the inner wall to remain cooled for optimal detector 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
This solution provides a compact, efficient gettering system that effectively absorbs hydrogen and water vapor at low temperatures, integrates radiation absorption, and reduces thermal mass, allowing for miniaturization and simplified construction while maintaining high sorption capacity and optical properties.
Implementation Method 1
a thin-layer laminate including at least one layer of substance(s) selected from the group consisting of platinum group metals and oxides thereof
Implementation Method 2
which absorbs hydrogen and water vapor
Implementation Method 3
at least one porous hydrophilic layer of a mixture of at least one active metal with at least one active metal oxide
Implementation Method 4
porous hydrophilic layer
Implementation Method 5
functions as an IR radiation absorber
Implementation Method 6
deposited on a substrate like aluminum or titanium
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(d)
Figure 3(a)~3(b)
AI summary
A vacuum enclosure which is defined by a wall having inner and outer surfaces, where the inner surface is in contact with the vacuum and the outer surface is in contact with ambient air, is characterized by presence therein of a getter for undesired gaseous contaminants, which comprises a substrate (either integral with the inner surface or not), and deposited thereon by vacuum deposition a thin-layer laminate including (α) at least one layer of substance(s) selected from the group consisting of platinum group metals and oxides thereof, and (β) at least one porous hydrophilic layer. A corresponding layered structure having utility as a getter is also part of the invention.