Abstract: Disclosed is an improvement of method and apparatus for varying the cross-section of a beam of electrically charged particles and projecting the so-varied beam onto the target. Passing through a plurality of apertured masks one after another, a beam of electrically charged particles is so deflected that the image of the overlapping area of the apertures of the masks appears on a target. According to this invention a beam of charged particles is deflected between two subsequent masks upstream so as to reduce the amount of beam current to that which is required in forming a desired image on the target, and the so-reduced beam is deflected between two subsequent masks downstream so as to trim and shape the cross-section of the beam into the exact and sharp contour as desired.The method and apparatus for varying and projecting a beam of electrically charged particles according to this invention are particularly useful in producing microcircuits.