Method for correcting astigmatism and focusing in charged particle optical lens-barrel

摘要

In a method for correcting astigmatism and focusing in a charged particle optical lens-barrel, according to the invention, Fourier transformation data items are obtained, which indicate images obtained by scanning a sample with a charged particle beam when the focal distance of an objective lens is set to each of at least two different values. Then, the configuration of the section of the beam is determined on the basis of the difference between the data items, thereby performing astigmatism correction and focusing. As a result, a charged particle microscope can perform highly accurate astigmatism correction and focusing during observation, irrespective of the surface configuration of the sample or the beam section on the sample.