AR Coatings

We use Ion Beam Sputtering for deposition of Dielectric antireflection (AR) coatings. A coating system was designed and built at Tecrys to provide high damage threshold AR coatings on LBO and other nonlinear crystals. A cryo-pumped chamber is equipped with two Ion Guns: one is for sputter deposition (three targets installed) and the second is for in-situ sputter cleaning of the crystals. Deposition rate and film thickness monitoring is performed using quartz oscillator. Dielectric multilayer structures are deposited in automated mode with run-to run reproducibility of layer thicknesses better than 2%. The reflection spectra of coatings is characterized on Shimadzu Spectrophotometer with the accuracy of 0.1%.

The OPTILAYER software package is used for coating design, layer/substrate characterisation and reverse engineering. LBO crystal tests and UV Laser damage threshold measurements are performed on YAG (15ns, 10Hz, 1064nm) and excimer (308nm, 12 ns, 1-100Hz) laser. All coating operations are performed in a clean room space.

Specifications:

• Material: LBO, other on request
• Coating technology: IBS with in-situ ion beam sputter cleaning
• Coating spectral range: 200 to 2000nm
• Damage Threshold:
  • >2GW/cm2 @ 15ns, 10Hz, 1064nm,
  • >500MW/cm2 @ 12ns, 10Hz, 308 nm
• Reflectivity:
  • VVV coating: <0.2% @1064nm, <0.3%@532nm, <0.4%@355nm
  • W coating: <0.1-0.05% on request