A charged-particle microscopy includes irradiating a sample in measurement sessions, each having an associated beam parameter (P) value detecting radiation emitted during each measurement session, associating a measurand (M) with each measurement session, thus providing a data set (S) of data pairs {Pn, Mn}, wherein an integer in the range of 1≦n≦N, and processing the set (S) by: defining a Point Spread Function (K) having a kernel value Kn for each value n; defining a spatial variable (V); defining an imaging quantity (Q) having fore each value of n a value Qn that is a three-dimensional convolution of Kn and V, such that Qn=Kn*V; for each value of n, determining a minimum divergence min D(Mn∥Kn*V) between Mn and Qn, solving V while applying constraints on the values Kn.