1. A method for observing a feature within a substrate using charged particle beam imaging, comprising: (a) directing an ion beam toward the substrate to expose a cross section including the feature; (b) directing a charged particle beam toward the cross section to obtain image information about the cross section; (c) analyzing the image information of the feature to determine parameters for carrying out an exposing of a subsequent cross section, the subsequent cross section including the feature, wherein the parameters include a size and shape of an area to be milled, a position of the substrate relative to the ion beam and the charged particle beam, or a combination thereof; and (d) carrying out the exposing of the subsequent cross section.