The invention relates to a charged particle detector system comprising a conversion plate (110) to convert incoming radiation to secondary electrons. These secondary electrons are then detected by a secondary electron detector (120), thereby providing information of the incoming radiation. Often this information is limited to, in first approximation, the flux of incoming radiation. In the case of, for example, backscattered electrons this is the current of the incoming backscattered electrons. The invention proposes to form the conversion plate as, for example, an energy dependent detector, for example a photodiode to detect electrons, so that the detector system simultaneously provides information of, for example, current (S1) and mean energy (S2) of the incoming radiation. The detector system is especially suited for use in a SEM or a DualBeam apparatus.