A method comprising: propelling a plurality of ion beamlets from a first grid with a substantially elliptical pattern of holes (360, 363, 366) 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 (361, 364, 367), 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 (360, 363, 366) 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 (361, 364, 367), 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.