The design of the Beam Expanders is based on a Galilean Telescope configuration which is corrected as an afocal system for use over a range of narrow wavebands. The wavefront illustrations give the design performance of these lenses. Apart from expanding a beam, this lens allows the control of laser beam divergence to produce smaller beam diameters at large distances. The adjustable mount and locking ring permit variable setting of the beam diameter over long distances.
