Method and apparatus for in-situ sample quality inspection in cryogenic focused ion beam milling

The invention relates to a method and a dual beam FIB/(S)TEM apparatus for in-situ sample quality inspection in cryogenic focused ion beam milling. The method comprises the steps of: 5 loading the sample into a sample holder of the dual beam. FIB/(S)TEM apparatus, wherein the (S)TEM apparatus comprises an electron column and a detector, wherein the sample holder is arranged in between the electron column and the detector; 10 obtaining an image of the electrons that have passed through the sample using the electron column to direct an electron beam towards the sample and using the detector to detect electrons passing through the sample; using a scattering pattern in said image of the 15 transmitted electrons to establish a measure for the thickness of the sample and to establish whether or not the image comprises a diffraction signal due to electron diffraction from ice crystals.