UV Optical Element Cleaning via Activated Hydrogen and Inert Gas
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Solution Overview
Problem
Optical elements for the ultraviolet wavelength range with metal-containing layers face degradation due to low oxygen or water concentrations, leading to contamination and oxidation, especially when protective coatings are damaged or absent.
Innovation Solution
A cleaning process involving the supply of activated hydrogen to reverse oxidation, followed by inert gas with a low H2O volume fraction to prevent re-oxidation, along with heating and optional use of cold traps or platinum areas to enhance drying and reduce water and oxygen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If activated hydrogen is supplied to clean the metal-containing layer surface, then oxidation is reversed and contaminations are removed, but the risk of renewed oxidation increases due to increased concentration of water, oxygen, hydroxide ions or hydroxyl radicals
Solution Approach 1:
The patent applies inert gas (such as nitrogen or noble gases) to create a protective atmosphere around the metal-containing layer surface during and after cleaning with activated hydrogen. This inert environment prevents oxygen and water from contacting the cleaned surface, thereby eliminating the renewed oxidation risk while maintaining cleaning effectiveness.
Solution Approach 2:
The patent performs preliminary cleaning with activated hydrogen to remove oxidations and contaminations before the metal-containing layer is exposed to potentially harmful environments. By completing the cleaning action first and then immediately protecting with inert gas, the surface is prepared in its cleanest state before any re-oxidation could occur.
2Reliability
If protective layer is applied to protect metallic layer, then oxidation protection is improved, but cleaning becomes more difficult and may damage protective coating
Solution Approach 1:
The patent uses activated hydrogen as an intermediary cleaning agent that can penetrate and clean through or between protective layers without damaging them. The activated hydrogen selectively removes oxidations and contaminations while leaving the protective coating intact, thus maintaining both protection and cleanability.
Solution Approach 2:
The patent changes the physical and chemical parameters of hydrogen (activating it through plasma, heating, or catalysis) to create a cleaning agent with specific properties that allow it to remove contaminants without attacking the protective layer. The activated hydrogen has higher reactivity toward oxidations but controlled interaction with the protective coating.
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
Effectively cleans and protects metal-containing surfaces by reversing oxidation and reducing contamination risks, suitable for both operational and maintenance phases, particularly for optical elements without complete protective coatings.
Implementation Method 1
Supplying activated hydrogen, i.e. hydrogen radicals or ionized hydrogen, results in contaminations being cleaned from the surface of the optical element. In particular, the oxidation of the metal-containing layer can be reversed.
Implementation Method 2
In order in this case to reduce the risk of renewed oxidation of the cleaned surface as a result of a concentration of water, oxygen, hydroxide ions or hydroxyl radicals, which is potentially increased as a result of the treatment with activated hydrogen, the atmosphere in the region of the surface of the optical element having a metal-containing layer is replaced by dry inert gas
Implementation Method 3
the activated hydrogen is supplied by molecular hydrogen being added to inert gas with a proportion of 1-20 vol. % and this mixture being guided past a heating wire arrangement or being exposed to dissociating radiation. By way of the action of heat or the dissociating radiation, the molecular hydrogen can be split into hydrogen radicals or else ionized.
Implementation Method 4
the molecular hydrogen can be split into hydrogen radicals or else ionized
Implementation Method 5
Advantageously, a cold trap and/or a drying agent and/or an area comprising a platinum metal are arranged in the vicinity of the surface having a metal-containing layer
Data Source
AI summary
Proposed for cleaning optical elements for the ultraviolet wavelength range having at least one metal-containing layer on a surface is a process that includes: —supplying activated hydrogen to the surface having the metal-containing layer; subsequently supplying inert gas having an H2O volume fraction of below 5 ppm, preferably below 1 ppm, particularly preferably below 0.2 ppm. To this end, an optical system (1) includes a housing (122), a supply line (161) of activated hydrogen, a supply line (162) of inert gas having an H2O volume fraction of below 5 ppm and a discharge line (163) for pumping gas out of the housing.