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An electrostatic system suffers generally from image plane curvature leading to defocusing in the peripheral image region if a flat viewing screen ( or interstage coupler ) is utilized, while a magnetic system requires accurate adjustment of the solenoid, which is heavy and bulky.

As it will be discussed later, peripheral defocusing can be improved on by utilizing curved fiber couplers.

It should be noted, however, that the paraxial resolution is quite similar for both electron optical systems.