So-called protective windows are the last optics to be used before the working area; they protect high-quality laser optics from material splatter. In the majority of cases, protective windows are available inexpensively with few demands regarding the surface figure and surface quality.
The windows are coated with an anti-reflex coating for the laser beam and, upon request, can also be AR coated for the pilot laser in the visible wavelength range.
Protective windows are available in the following materials:
- BK7 or similar for the simplest application
- Quartz glass for lasers with higher output power
