Abstract: The invention relates to a monochromator on the basis of Wien filters. According to a first aspect, four Wien filters are arranged in series along a common optical axis of which the two center Wien filters are each rotated by 90° relative to the two outer Wien filters. The two center Wien filters (W2, W3) are orientated simultaneously anti-parallel to each other. Such a monochromator has inherent stigmatic imaging characteristics and is, as a unit, free of dispersion. According to a further aspect, each of the Wien filters is configured symmetrically with reference to a 90° rotation about the optical axis. The magnetic and the electrostatic poles of the Wien filter are identically dimensioned so that the orientation of the Wien filter azimuthally about the optical axis (OA) can be varied by a corresponding drive of the particular contacts for the voltage supply and current supply of the electrodes and coils.

Abstract: The invention relates to a monochromator on the basis of Wien filters. According to a first aspect, four Wien filters are arranged in series along a common optical axis of which the two center Wien filters are each rotated by 90° relative to the two outer Wien filters. The two center Wien filters (W2, W3) are orientated simultaneously anti-parallel to each other. Such a monochromator has inherent stigmatic imaging characteristics and is, as a unit, free of dispersion. According to a further aspect, each of the Wien filters is configured symmetrically with reference to a 90° rotation about the optical axis. The magnetic and the electrostatic poles of the Wien filter are identically dimensioned so that the orientation of the Wien filter azimuthally about the optical axis (OA) can be varied by a corresponding drive of the particular contacts for the voltage supply and current supply of the electrodes and coils.