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Improvement in Laser-Induced Damage Threshold of Antireflection Coatings for High-Power UV Lasers by Removing Subsurface of Large lenses

We improved the laser-induced damage threshold (LIDT) of antireflection coatings for a wavelength of 355 nm by removing the subsurface of the substrate with an ion beam etching system. The ion beam etching system is set up in a coating chamber to etch 1000 mm optics uniformly. The antireflection coating composed of MgF2, Al2O3 and SiO2 layers has an excellent LIDT of 9.2 J/cm2 which is the highest reported LIDT in the world (355 nm, 0.3 ns pulsed laser).