KrF, XeCl, XeF Lasers (248 nm, 308 nm, 351 nm)

Cavity Mirrors

Fig.1:Reflectance spectrum of a 308 nm cavity mirror

Oxide coatings for high mechanical stability
Coatings can be produced by IAD, magnetron sputtering or IBS

Fluorine Resistant Cavity Mirrors

Fig.2:Reflectance spectrum of a fluoride KrF cavity mirror

Fluoride coatings and CaF₂ substrates for high stability against fluorine and chlorine
Laser mirrors with R > 98 % at 248 nm, 308 nm and 351 nm

Output Couplers

Fig.3:Reflectance spectrum of an output coupler with R (0°, 308 nm) = 50 % ±3 %

PR coatings with tolerances of
- ±2 % for R = 10 % … 30 %
- ±3 % for R = 30 % … 75 %
- ±2 % for R = 75 % … 90 %
- and ±1 % for R > 90 %

Fluorine Resistant Output Couplers

Fig.4:Reflectance spectrum of a fluoride output coupler with
R (0°, 248 nm) = 25 % ±3 %

PR coatings with tolerances of:
- ±2 % for R = 10 % … 20 %
- ±3 % for R = 20 % … 75 %
- and ±2 % for R = 75 % … > 90 %

Windows and Lenses

Fig.5:Reflectance spectra of an AR coating for 308 nm
and AOI = 0° – 30°

High quality mirror substrates, windows and lenses of Fused Silica

Turning Mirrors

Fig.6:Reflectance spectra of a turning mirror for 308 nm produced by IBS (Reflectance measurement in s- and p-polarization by CRDS)

Table 1:Reflectance of Turning Mirror

Coating	R (AOI = 0°)	Rs (AOI = 45°)	Rp (AOI = 45°)
248 nm IAD	> 99.0 %	> 99.5 %	> 99.0 %
248 nm sputtering	> 99.7 %	> 99.8 %	> 99.6 %
308 nm IAD	> 99.7 %	> 99.8 %	> 99.5 %
308 nm sputtering	> 99.9 %	> 99.9 %	> 99.7 %
351 nm IAD	> 99.9 %	> 99.9 %	> 99.7 %
351 nm sputtering	> 99.95 %	> 99.95 %	> 99.9 %

Attenuators

Fig.7:Transmittance spectrum of a sputtered attenuator (IBS) for 308 nm with exactly adjusted and thermally stable transmittance of T = 0.08 % at AOI = 45° (unpolarized light)

LIDT and Lifetime Data

Table 2:LIDT of Oxide Coatings

Coating	LIDT* [J/cm²]
HR (0°, 248 nm) IAD	10 J/cm² (1-on-1) 5 J/cm² (1000-on-1)
HR (45°, 248 nm) IAD	10 J/cm² (1-on-1)
* Measurements were performed at Laser Labor Göttingen and at Friedrich-Schiller-University Jena

Table 3:Lifetime of Fluoride Coatings

Coating	Lifetime
HR (0°, 248 nm)	2 × 10⁸ pulses*
PR (0°, 248 nm) = 50 %	2 × 10⁸ pulses*
AR (0°, 248 nm)	2 × 10⁸ pulses**
HR (0°, 308 nm)	2 × 10⁸ pulses**
HR (0°, 351 nm)	2 × 10⁸ pulses**
PR (0°, 351 nm) = 25 %	2 × 10⁸ pulses**
* Energy density: 100 mJ/cm², repetition rate: 100 Hz, pulse duration: 15 ns; tested at COHERENT AG, München
** Energy density: 55 mJ/cm², repetition rate: 100 Hz, pulse duration: 15 ns; tested at COHERENT AG, München

KrF, XeCl, XeF Lasers (248 nm, 308 nm, 351 nm)