248nm
Mirrors
Fluorine Resistant Output Couplers
Fluorine Resistant Windows
Technical Data of KrF Laser Components
Window
Mirrors
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- Fluoride coatings and CaF2 substrates for high stability against fluorine and chlorine.
- Laser mirrors (R > 98% at 248 nm, 308 nm and 351 nm).
Turning Mirror [ Angle of Incidence=45°, Polarisation : u,s,p-Pol. HRu ( 45°, 248nm) > 99.5%, HRs ( 45°, 248nm) > 99.7%, HRp ( 45°, 248nm) > 99% ]
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| Reflection Spectrum |
Fluorine Resistant Output Couplers
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- PR coatings with tolerances of
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- ± 2 % for R = 10 % … 30 %
- ± 3 % for R = 30 % … 75 % and
- ± 2 % for R = 75%…>90%.
Fluorine Resistant Windows
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- High quality mirror substrates, windows and lenses of CaF2 (248 nm excimer grade or UV quality, HELLMA Materials GmbH).
- Extended lifetimes at high energy densities at 248 nm.
Technical Data of KrF Laser Components
| Coating | Materials | Reflectance | Damage threshold* | Lifetime test |
| HR (0°, 248 nm) | oxides | > 99 % | 10 J/cm2, 1 – on – 1,20 ns 5 J/cm2, 1000 – on – 1 | |
| HR (45°, 248 nm) | oxides | > 99 % (random pol.) | 10 J/cm2, 1 – on – 1,20 ns | |
| HR (0°, 248 nm) | fluorides | R > 98 % | 2 x 108 pulses ** | |
| PR (0°, 248 nm) | fluorides | R = 50 ± 3 % | 2 x 108 pulses ** | |
| PR (0°, 248 nm) | fluorides | R < 0.25 % | 2 x 108 pulses ** |
* Measurements were performed at Laser Labor Göttingen and at Friedrich-Schiller-Universität Jena
** Energy density: 100 mJ/cm2, rep. rate: 100Hz, pulse duration: 15ns; tested at COHERENT AG, München
Window
Angle of Incidence=0°, Coating on Fused Silica 248nm excimer grade AR(0°, 248nm)<0.25%.
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| Transmission Spectrum |