Deutsch
Kompetenzen
Kompetenzen〉 Laserkomponenten〉 Bauteile für ArF Laser

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 (193 nm excimer grade) 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

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°, 193 nm), R < 0.25 %CaF24 – 5 J/cm22.5 x 108 pulses, no damage**
AR(0°, 193 nm), R < 0.25 %fused silica2 – 3 J/cm2 
PR(0°, 193 nm), R = 25 %CaF23 – 4 J/cm22.5 x 108 pulses, no damage**
PR(0°, 193 nm), R = 50 %CaF22 – 3 J/cm2109 pulses***
HR(0°, 193 nm), R > 96 %CaF22 – 3 J/cm2 109 pulses***, no damage
1010 pulses****, no damage
4 x 109 pulses*****, no damage
HR(45°, 193 nm), R > 95 % (random polarized) CaF22 – 3 J/cm2 
Oxide coatings 
HR(0°, 193 nm), 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