A method comprising: propelling a plurality of ion beamlets from a first grid with a substantially elliptical pattern of holes in an elliptically asymmetric distribution of steering angles; propelling the plurality of ion beamlets towards a second grid with a substantially elliptical pattern of holes , the second grid downstream of the first grid, wherein each steering angle is achieved by offsetting holes in the second grid relative to corresponding holes in the first grid, whereby a first hole of the second grid is offset relative to a corresponding first hole of the first grid, and the first offset yields a first predetermined steering angle of a first ion beamlet, and a second hole of the second grid is offset relative to a corresponding second hole of the first grid, and the second offset yields a second predetermined steering angle of a second ion beamlet, and at a radius from the center of the second grid the first predetermined steering angle is different from the second predetermined steering angle; and propelling the plurality of ion beamlets towards a third grid with a substantially elliptical pattern of holes, the third grid downstream of the second grid, wherein the first ion beamlet passes through a first hole of the third grid, and the second ion beamlet passes through a second hole of the third grid, wherein the first grid has a same applied voltage polarity as a charge polarity of individual ions of the plurality of ion beamlets, and the second grid has an applied voltage polarity opposite of a charge polarity of the individual ions of the plurality of ion beamlets. propelling a plurality of ion beamlets from a first grid with a substantially elliptical pattern of holes in an elliptically asymmetric distribution of steering angles; propelling the plurality of ion beamlets towards a second grid with a substantially elliptical pattern of holes , the second grid downstream of the first grid, wherein each steering angle is achieved by offsetting holes in the second grid relative to corresponding holes in the first grid, whereby a first hole of the second grid is offset relative to a corresponding first hole of the first grid, and the first offset yields a first predetermined steering angle of a first ion beamlet, and a second hole of the second grid is offset relative to a corresponding second hole of the first grid, and the second offset yields a second predetermined steering angle of a second ion beamlet, and at a radius from the center of the second grid the first predetermined steering angle is different from the second predetermined steering angle; and propelling the plurality of ion beamlets towards a third grid with a substantially elliptical pattern of holes, the third grid downstream of the second grid, wherein the first ion beamlet passes through a first hole of the third grid, and the second ion beamlet passes through a second hole of the third grid, wherein the first grid has a same applied voltage polarity as a charge polarity of individual ions of the plurality of ion beamlets, and the second grid has an applied voltage polarity opposite of a charge polarity of the individual ions of the plurality of ion beamlets. <EOS>