Optimized curvilinear variable axis lens doublet for charged particle beam projection system

A method of making an optimized charged particle beam projection system with a lens system comprising a telecentric antisymmetric doublet comprising the steps as follows:

• specifying lens configuration including a collimator lens, a projector lens, and first order optics and then calculating lens excitations;
• configure the lens system thereby providing lens field distributions, and beam landing angle axis cross-over of an imaging ray;
• providing an input of a configuration of deflectors formed surrounding and coaxial with the collimator lens and the projector lens including an axial location of the deflectors, then solving a linear equation set, and thereby provide a curvilinear axis and associated deflection field distributions;
• then calculating third order aberration coefficients yielding a list of up to 54 aberration coefficients;
• providing an input of dynamic correctors, then calculating excitations to eliminate quadratic aberrations in deflection, then calculating third and fifth order aberrations, providing image blur and distortion vs. deflection, best focal plane, and depth of focus;
• then testing to determine whether a current result is better than a previous result, if the current result is better than the previous result then changing the input for the axial location of the deflectors to solve the linear equation set again, and otherwise testing whether the current result is acceptable;
• if the current result is other than acceptable, then providing a new deflector configuration input to again solve the linear equation set and continuing through the steps thereafter;
• if the current result is acceptable, then testing whether the deflection current is larger;
• and
• if the deflection current is larger, then changing the input for the axial location of the deflectors to solve the linear equation set again, and if otherwise then END the process.