In box 520, the charged particle beam is directed through an electrode arrangement that includes a first electrode provided on a first electric potential and a second electrode provided on a second electric potential different from the first electric potential. The electrode arrangement may be an electrostatic lens. A distance between the first electrode and the second electrode along the optical axis A may be 10 mm or less, particularly 5 mm or less, and a potential difference between the first electrode and the second electrode may be 9 kV or more.

A first spacer element, particularly a ceramic ball, is sandwiched between the first electrode and the second electrode and aligns the first electrode and the second electrodes relative to each other. In particular, three spacer elements may be sandwiched between the first electrode and the second electrode for aligning the first electrode and the second electrode relative to each other, particularly for ensuring that the first electrode and the second electrode are parallel to each other and/or have a predetermined distance from each other.

In box 530, electrical field lines are bent away from a point of contact between the first electrode and the first spacer element (more particularly: from a triple point) with a first conductive shield that is provided in a first blind hole of the first spacer element. A contact assembly as described herein may protrude from the first electrode into the first blind hole and provide an electrical contact between the first electrode and the first conductive shield.

In box 540, the charged particle beam 105 may be focused on a specimen, and signal particles emitted by the specimen may be detected by a detector.