a precision printing system uses multiple scan beams that an acousto - optic modulator separately modulates . an array of optical elements such as dove prisms separately rotates each of the beams about a central ray of the beam to eliminate blurred edges , skew , and variations in line thickness caused by the direction of propagation of acoustic waves in the aom being at an angle to a scan direction . in particular , the amount of rotation is selected so that in the final image the direction in which illumination progresses across a cross - section of a beam is in a direction opposite the scan direction . a method of making the array includes attaching rods to a flat , grinding or polishing the combination of the rods and flat to form three planar regions that correspond to facets on prisms . removing the rods / prisms from the flat . using photolithography and etching to form grooves in a substrate , and a mounting the rods / prisms in the grooves on the substrate . integrated circuit processing techniques that control the spacing , widths , and depths of the grooves provide precise control of critical alignment of the prisms .