A laser welding beam transport system is provided in which the laser beam 14 emanating from the laser generator 10 is expanded in diameter in an expander 16 at a location close to the generator, and then is transported in its expanded diameter to a remote location where the beam is reduced in diameter in a beam reducer 26 at a location close to the welding station 28 for the purpose of maintaining a relatively constant power density of the beam at the station over a significant range of working travel of the working station.