Patent ID: 7385205

Claim:
A charged particle beam apparatus comprising: a source for emitting a charged particle beam; a scanning deflection unit to scan the beam of charged particles over a specimen; a first aperture alignment deflection unit to shift the beam with respect to an optical axis of the charged particle beam apparatus; a second aperture alignment deflection unit to redirect the beam with respect to an optical axis of the charged particle beam apparatus; an objective lens defining the optical axis of the charged particle beam apparatus; a voltage supply changing the energy of the beam of charged particles; a detector for imaging a plurality of frames; a synchronization control unit for synchronizing a frequency of the voltage supply and an imaging frequency of the plurality of frames; and an image processor connected to the detector to carry out a calibration of the first aperture alignment deflection unit and the second aperture alignment deflection unit based on an image shift of a set of images constituted by a plurality of the frames.