Method for performing focusing in a particle-optic

专利名称：Method for performing focusing in a
particle-optical device with the aid of
astigmatism in the particle beam
发明人：Maes, Willem Hendrik,Van Vlucht, Robertus Johannes Michael,Sterken, Hendrikus P. M.申请号：EP04077317.8
申请日：20040816
公开号：EP1511065B1
公开日：
20120411
专利内容由知识产权出版社提供
摘要：In a particle-optical device such as an electron microscope it is advantageous to perform the process of focusing automatically. In accordance with the invention, the electron beam which is to be focused is deliberately made astigmatic to a certain degree. With this astigmatic beam, two images of a specimen are made at two different settings of the objective, after which in each of the images the direction of the astigmatic smearing is determined - for example, with the aid of a two-dimensional Fourier transform (FFT). The directions of the astigmatic smearing are perpendicular to each other if, in the transition from a first setting of the objective to a second one, the point of optimum focus is passed. Through a process of interpolation (which process may be iterative) between these two settings, the point of optimum focus can now be determined. Possible anisotropy in the specimen itself can be eliminated by making two images at both of the settings of the objective and by subtracting the FFTs thereof from each other.
申请人：FEI CO
地址：US
国籍：US
代理机构：Bakker, Hendrik 更多信息请下载全文后查看。