The invention relates to a charged-particle microscope comprising a charged-particle source; a sample holder; a charged-particle lens system; a detector; and a beam pulsing device, for causing the beam to repeatedly switch on and off so as to produce a pulsed beam. The beam pulsing device comprises a unitary resonant cavity disposed about a particle-optical axis and has an entrance aperture and an exit aperture for the beam. The resonant cavity is configured to simultaneously produce a first oscillatory deflection of the beam at a first frequency in a first direction and a second oscillatory deflection of the beam at a second, different frequency in a second, different direction. The resonant cavity may have an elongated (e.g. rectangular or elliptical) cross-section, with a long axis parallel to said first direction and a short axis parallel to said second direction.