A beam separator device (200) is described. The beam separator device (200) includes a first deflector (112) providing a first magnetic deflection field (B1) for deflecting a charged particle beam (101) propagating along a beam entrance axis (A1) by a first deflection angle (α1); a second deflector (114) arranged downstream from the first deflector (112) providing a second magnetic deflection field (B2) for deflecting the charged particle beam by a second deflection angle (α2) in the direction of an intermediate beam axis (A2), wherein the second deflector (114) is configured for deflecting the charged particle beam (102) re-entering the beam separator device (200) along the intermediate beam axis (A2) by a third deflection angle (α3); a third deflector (212) arranged downstream from the second deflector (114) providing a third magnetic deflection field (B2) for deflecting the charged particle beam (102) by a fourth deflection angle (α4) in the direction of a beam exit axis (A3); a first rotation-free lens to be arranged at a first crossover (X1) of the charged particle beam between the first deflector (112) and the second deflector (114) for at least partially compensating for a dispersion introduced by at least one of the first deflector and the second deflector; and a second rotation-free lens to be arranged at a second crossover (X2) of the charged particle beam between the second deflector (114) and the third deflector (212) for at least partially compensating for a dispersion introduced by at least one of the second deflector and the third deflector.