Excimer Mirrors

When lasers are used in the UV range (excimer lasers), the optics are exposed to very high energies. In addition, excimer lasers run in pulsed mode and generate extremely short pulses with high peak intensities. For this reason, excimer optics must have high damage thresholds and be durable. Excimer lasers are gas lasers and are often operated with fluorine. If an optic exposed to the process gas, the substrate and coatings must also be based on fluorine, otherwise they would dissolve.

Example:   Schematischer Aufbau eines Excimerlasers

LAYERTEC produces optics for all excimer lasers (F₂ laser 157 nm, ArF laser 193 nm, KrF laser 248 nm, XeCl laser 308 nm, XeF laser 351 nm). Resonator mirrors and output coupling mirrors for fluorine-based lasers consist of CaF₂ or MgF₂ substrates with fluoride coatings and can also be used in direct contact with the laser gas. Output coupling mirrors are typically offered with reflectivities up to R = 50 %. The specified reflectance is achieved with an accuracy of ±3 %.

Deflection mirrors for 157 nm and 193 nm are also based on fluoride layer systems on CaF₂ substrates. This guarantees a high damage threshold and a long lifetime. Deflection mirrors for wavelengths from 248 nm consist of UV-compatible oxide layer systems on quartz glass substrates. Beam delivery optics can be designed for any angle of incidence. Deflection mirrors for 45° angles of incidence are available as standard components.