The Galilean type beam expanders with thin UV FS lenses suitable for femtosecond applications. Fixed Ratio Beam Expanders are designed to increase the diameter of a collimated input high power laser beam to a larger collimated output beam. Fixed Ratio Beam Expanders can be adjusted for the input beam divergence angle to obtain collimated, divergent or focused beam at the output. They feature non-rotating divergence adjustment by sliding lens design.