Junri Ishikura

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).

Compact Coating Machine for Large Laser Optics with a New Thickness-Distribution Equalization Method

A compact coating machine with which large optics up to 1000 mm in diameter and 300 kg in weight can be coated uniformly is presented. In order to achieve a uniform thickness distribution within the compact coating chamber, we devised a new thickness equalization method that utilizes a rotating mask between an evaporation source and a large rotating optics at the center of the coating chamber.