12 with 2 to 4 kv voltage in the position where the scintillator was in the first version attracts and accelerates the se emerging from the sample and collected by the sparse grid 11 to scintillator direction a sparse cylindrical grid in the form of rings 14 surrounds the path to the scintillator a low positive voltage 100 v to 500 v on this sparse ring grid attracts se3 from large regions of the vacuum chamber walls and other surfaces within the chamber while a negative potential on this grid excludes these se3s at the end of the se3 grid there is a conical shaped cylindrical electrode 15 at the same voltage as the se3 grid it shapes the electrical field to insure that all collected se3 or se will hit the scintillator 16 simulation of the trajectory of se from the sample and se3 from other parts of the chamber are shown in fig1 and fig1 it is shown that all se reach the scintillator with se3 rejected or by switching voltages all se3 reach the scintillator and se are rejected according to one aspect of this embodiment switching grid voltages is used to measure either se from the sample with high efficiency and exclude se3 or measure se3 and exclude all direct se thereby allowing the generation of bse images without using a dedicated bse detector this version of the detector is suitable for any focused scanning e beam device such.