VUV Optical Element Fluorine Scavenger Layer
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Solution Overview
Problem
Optical elements in the VUV wavelength range face challenges with degradation due to irradiation, particularly at wavelengths below 160 nm, where defects are generated in fluoride layers leading to fluorine loss and oxidation, reducing their lifetime.
Innovation Solution
Incorporating a fluorine scavenger layer doped with metallic dopant ions, such as Gd3+, to reduce the mobility of interstitial fluorine atoms, thereby interrupting the degradation process and extending the lifetime of optical elements by forming complexes that bind fluorine ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoride layers are used for VUV wavelength range, then optical performance is achieved, but degradation occurs due to fluorine loss and oxidation reducing lifetime
Solution Approach 1:
A protective coating layer is applied to the fluoride layer to act as an intermediary barrier. This coating prevents direct interaction between the fluoride layer and the VUV irradiation environment, blocking the harmful one-photon processes that generate defects and cause fluorine loss. The coating serves as a mediator that protects the underlying fluoride optical element from degradation while maintaining optical performance.
Solution Approach 2:
The patent introduces a gas inlet designed to supply an adsorbate (especially water) to the interior of the optical arrangement during irradiation. This creates a controlled inert-like atmosphere that alleviates the degradation of the fluoride layer surface by providing a protective environment against oxidation and other harmful chemical reactions induced by VUV irradiation.
2Duration of action of stationary object
If protective coatings are applied to fluoride layers, then lifetime is extended, but optical performance may be compromised
Solution Approach 1:
The patent carefully controls the parameters of the protective coating, including its composition, thickness, and structural properties. By optimizing these parameters, the coating provides adequate protection against degradation while maintaining sufficient transparency and optical performance in the VUV wavelength range. The gas supply parameters are also controlled to achieve the optimal balance between protection and optical function.
3Reliability
If frequent replacements are made to maintain performance, then optical performance is maintained, but productivity decreases
Solution Approach 1:
The protective coating and gas supply system are implemented in advance to prevent degradation before it occurs. This preliminary protective action extends the operational lifetime of the optical element, allowing it to maintain performance for longer periods without requiring replacement. The system proactively protects against degradation mechanisms rather than reacting to performance loss.
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 fluorine scavenger layer significantly prolongs the lifetime of optical elements by preventing fluorine diffusion and oxidation, reducing the need for frequent replacements and minimizing the use of protective gases, while maintaining optical performance.
Implementation Method 1
Incorporating a fluorine scavenger layer doped with metallic dopant ions, such as Gd3+, to reduce the mobility of interstitial fluorine atoms
Implementation Method 2
thereby interrupting the degradation process and extending the lifetime of optical elements by forming complexes that bind fluorine ions
Implementation Method 3
Absorption of radiation in the VUV wavelength range with energies close to the band edge of fluoride, and then excitation of electrons into the conduction band
Implementation Method 4
in the case of irradiation at these wavelengths, the energy of the light is sufficient to generate defects in the layer via one-photon processes
Implementation Method 5
Relaxation of the previously excited electrons with release of the energy difference to the ionic lattice (color centers)
Implementation Method 6
Diffusion of fluorine atoms and loss of fluorine via the surface
Data Source
AI summary
An optical element (7, 8) for the VUV wavelength range includes a substrate (7a, 8a), and a coating (15) applied to the substrate (7a, 8a). The coating (15) has at least one fluorine scavenger layer (17, 17a, . . . , 17n) having a fluoride material (Mx+Fx−) doped with at least one preferably metallic dopant ion (Ax+). Also described are an optical arrangement that includes at least one such optical element (7, 8), as well as a method for producing such an optical element (7, 8).