LASER COMPONENTS manufactures partially reflective dielectric mirrors in house as standard in the wavelength range 193nm to 3um. 45° beam-splitters and 0° output couplers are produced routinely, with custom angles of incidence upon request. Output couplers are used primarily within resonators, using an optimised degree of reflectivity in order to extract the laser beam.
A partially reflective mirror coating is used on the front face and an anti-reflection coating on the rear face in order to minimise losses in the transmitted beam. For excimer lasers, output couplers used outside of the laser cavity generally use a fused silica substrate.
For output couplers inside of the resonator however, the coating and substrate must be chlorine or fluorine resistant due to exposure to the laser gas. In this case it is necessary to use CaF2 or MgF2 as a substrate. Coatings on these substrates exhibit a similar spectral performance to that of a standard coating on a fused silica substrate.