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.