Bauteile für ArF Laser

Mirrors, Output Couplers and Lenses

  • All fluoride systems guarantee high reflectivities and high damage thresholds
  • 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 %
  • High quality mirror substrates, windows and lenses of CaF2 (193nm excimer grade, SCHOTT AG) and fused silica
  • Development and production of customer specific components such as beamsplitters and variable attenuators on request
  • Single wavelength AR coating with residual reflectivities of R < 0.25% at AOI = 0° and R < 0.6 % at AOI = 45° (unpolarized light)
  • Broadband and multiple wavelength AR coatings
silver mirror for fs-lasersFigure 1: Measured reflectance and transmittance spectra of a turning mirror (AOI = 45°) for 193 nm for random polarized light (a) and a CaF2 window coated on both sides with a fluoride AR coating for 193 nm (b)

Variable Attenuators

  • Attenuators with different transmission ranges on request
  • Attenuators can be delivered with AR coated compensation plates of CaF2 of fused silica
silver mirror for fs-lasersFigure 2: Measured transmittance spectra of a variable attenuator at different AOI (a) and transmittance vs. AOI (b); the transmittance varies from T > 88 % at AOI = 0° to T < 2 % at AOI = 45°

Aluminium Mirrors

  • Enhanced aluminum mirrors:
    • Rp > 93%
    • Rs > 99%
    • Rr > 96%
  • For more information on Al mirrors see pages 96 – 97 in our catalog.
silver mirror for fs-lasersFigure 3: Measured reflectance spectra of a protected Al mirror optimized for 193nm (a) and an enhanced Al mirror for 193 nm, AOI = 45° (b)

Technical Data of standard ArF Laser Components

CoatingSubstrateDamage threshold*Lifetime test
Fluoride coatings
AR (0°, 193nm) R < 0.25%CaF24 – 5 J/cm22.5 x 108 pulses, no damage**
AR (0°, 193nm) R < 0.25%fused silica2 – 3 J/cm2
PR (0°, 193nm) R = 25%CaF23 – 4 J/cm22.5 x 108 pulses, no damage**
PR (0°, 193nm) R = 50%CaF22 – 3 J/cm2109 pulses***
HR (0°, 193nm) R > 96%CaF22 – 3 J/cm2 109 pulses***, no damage
1010 pulses****, no damage
4 x 109 pulses*****, no damage
HR (45°, 193nm) R > 95% (random polarized) CaF22 – 3 J/cm2
Oxide coatings
HR (0°, 193nm) R>92%fused silica<1 J/cm2
* 1000 - on -1, 14 ns; measurements were performed at Laser Labor Göttingen and at Friedrich - Schiller - Universität Jena
**Energy density: 18 mJ/cm2, repetition rate: 4 kHz, pulse duration: 30 ns; tested at COHERENT AG, Göttingen
***Energy density: 55 mJ/cm2, repetition rate: 1 kHZ, pulse duration 15 ns; tested at COHERENT AG, München
****Energy density: 27 mJ/cm2, repetition rate: 4 kHz, pulse duration: 30 ns; tested at COHERENT AG, Göttingen
*****Energy density: 80 mJ/cm2, repetition rate: 1 kHz, pulse duration: 12 ns; tested at COHERENT AG, München