Apparatus for determining the energy of charged particles

In a device for measuring the energy of charged particles separated from a sample by bombardment with ionizing radiation, which device includes an energy analyzer and an electron lens system disposed between the sample location and the analyzer and including a charged particle deceleration path, the electron lens system is composed of two individual lenses producing an intermediate image between them, with the deceleration path being located between the two lenses to contain the plane of such intermediate image