If you have a task to build up a beam expander or reducer, at least a couple of lenses will be needed. If an optical line has to withstand high energy density, reflecting elements are preferred over refractive optics. Reflecting focusing and defocusing optics are also perfect when dealing with ultrashort pulses. Concave and convex substrates, which are listed below, can be coated with gold, silver or aluminum. Laser line or broadband dielectric coatings on these substrates are also available. If necessary, latter coatings can feature optimized GDD values.