High-Power Laser Optics - Excimer Laser Mirrors

When excimer lasers are used in the ultraviolet range, optical components are subjected to very high energy. Additionally, excimer lasers operate in pulsed mode, producing extremely short pulses and high peak intensities. Consequently, excimer laser mirrors must have a high damage threshold and durability. Excimer lasers are gas lasers that frequently use fluorine. If an optical component is exposed to the process gas, both the substrate and coating must be fluorine-based; otherwise, they will dissolve.

Bena Optics manufactures optical components for all excimer lasers (F2 lasers at 157nm, ArF lasers at 193nm, KrF lasers at 248nm, XeCl lasers at 308nm, and XeF lasers at 351nm). Resonator mirrors and output couplers for fluorine-based excimer lasers are made from CaF2 or MgF2 substrates with fluorinated coatings, allowing them to be used in direct contact with the laser gas. Output couplers typically provide reflectivity up to R=50%. The specified reflectivity accuracy is ±3%.

Deflection mirrors for 157nm and 193nm wavelengths are also based on fluorinated layer systems on CaF2 substrates. This ensures a high damage threshold and long service life. Deflection mirrors for wavelengths above 248nm are made from UV-compatible oxide layer systems on quartz glass substrates. Beam delivery optics can be designed for any angle of incidence. Deflection mirrors with a 45° angle of incidence are provided as standard components.