A charged particle analyzer (1) comprises a first non-imaging electrostatic lens (8, 9) for receiving charged particles having divergent, trajectories and for converting the said trajectories into substantially parallel trajectories. At least one planar filter (10) is provided for receiving the charged particles having the substantially parallel trajectories and for filtering the charged particles in accordance with their respective energies. A second non-imaging electrostatic lens (11) receives the energy filtered charged particles and selectively modifies their trajectories as a function of their energies. A charged particle detector (12) then receives the charged particles in accordance with their selectively modified trajectories.