Cavity Optics

End Mirror

The output coupler usually has reflectance in the range 40% to 70%. In order to optimize power and spatial profile of the laser beam, the output coupler and rear mirror have optical surfaces with well-defined radii of curvature. The output coupler is typically composed of ZnSe in order to minimize absorption and thermal distortion while transmitting a high-power laser beam. The end mirror usually has reflectance 99.5% which means that the transmitted laser beam has low power. However, because absorption in the coating is higher than in the output coupler, substrate materials, such as Germanium or Gallium Arsenide, with high thermal conductivity are used in most lasers.

Folding Mirror

Total Reflectors are quite similar to turning mirrors. However, durability of the coating is more critical because the total reflectors are exposed to the gas discharge and the extremely high laser power density inside the cavity. Therefore, the coating must have best-possible environmental resistance and low absorption in order to minimize thermal distortion.

Partial Reflector

The output coupler usually has reflectance in the range 40% to 70%. In order to optimize power and spatial profile of the laser beam, the output coupler and end mirror have optical surfaces with well-defined radii of curvature. The output coupler is typically composed of ZnSe in order to minimize absorption and thermal distortion while transmitting a high-power laser beam. The end mirror usually has reflectance 99.5% which means that the transmitted laser beam has low power. However, because absorption in the coating is higher than in the output coupler, substrate materials, such as Germanium or Gallium Arsenide, with high thermal conductivity are used in most lasers.