A method for focusing a charged particle beam, the method includes: (a) altering a focal point of a charged particle beam according to a first focal pattern while scanning a first area of a sample and collecting a first set of detection signals; (b) altering a focal point of a charged particle bean according...http://www.google.com/patents/US7535001?utm_source=gb-gplus-sharePatent US7535001 - Method and system for focusing a charged particle beam
