For efficient deposition of thin films using ion beam sputtering, a high ion current density is desired. We have redesigned the ion extraction optics of a broad beam multiaperture ion source to focus the beam to a 2.5-cm-diam target area. Two focusing methods are described. One uses spherically dished grids, current densities of Ar+ up to 26 mA cm−2 at 1000 eV are acheived at a focal distance of 13 cm, etching a Si target up to 300 Å s−1. The average current density over the target area is 7.7 mA cm−2, more than six times the current density delivered by a parallel beam system with the same aperture dimensions.