Abstract: The present invention relates to a solution for solving an ill-posed inverse problem in image analysis, e.g. in an electron tomography application in order to recover a structure of a sample. The solution is provided for instance as a method comprising steps of determining reliable prior knowledge about the solution, determining initial guess for the solution and determining the corresponding forward operator, deciding upon model of stochasticity, deciding on suitable regularization method, deciding on updating scheme, and producing a sequence using the set configuration.

Abstract: To provide an aberration correction configuration that can realize both an aberration correction function for a long focus and an aberration correction function for a short focus. While having a conventional aberration correction apparatus configuration that has two rotationally symmetric lenses arranged between two multipole lenses, three rotationally symmetric lenses are disposed between an objective lens and a multipole lens instead of the conventional arrangement in which two rotationally symmetric lenses are disposed therebetween. When using the objective lens with a long focal length, aberrations are corrected using two rotationally symmetric lenses among three rotationally symmetric lenses disposed between the objective lens and the multipole lens. When using the objective lens with a short focal length, e.g.