methods and apparatus for reconfiguring a generally elliptically shaped beam produced by a laser diode bar into a single modified beam of substantially symmetrical shape . the methods and apparatus include the provision and utilization of a prism assembly which includes an entrance aperture , an exit aperture , and four total internal reflection surfaces . an incident beam is totally reflected at the total internal reflection surfaces step by step and is chopped into a specific number of parts which have the same width as that of the exit aperture from which they emerge stacked one on top of another . three embodiments , according to the types of prism assemblies and entrance and exit apertures , are presented .