Beam evaluation

The invention relates to a method for evaluating a charged particle beam and a method for controlling a charged particle beam. Furthermore, this invention relates to an apparatus for the examination of specimen with a beam of charged particles. The present invention provides, according to a first aspect, a method for automatically evaluating the performance of a charged particle device. The method uses a signal coming from a gold-on-carbon reference target. From this signal the spot size of the particle beam is determined. The method according to the present invention has the advantage that it does not depend on operator judgment. Therefore, the method leads to improved consistency, accuracy and reliability of the beam characterization, and, accordingly, to a better characterization of the quality of the system's performance.