Abstract: Disclosed is a device for, in combination with a stop having an aperture, generating charged particle beam pulses, an apparatus for inspecting a surface of a sample, and a method for inspecting a surface of a sample. The device includes a deflection unit which is arranged for positioning in or along a trajectory of a charged particle beam. The deflection unit is arranged for generating an electric field for deflecting said charged particle beam over the stop and across the aperture. The device also includes an electrical driving circuit for providing a periodic signal. The electrical driving circuit is connected to the manipulation unit via a photoconductive switch, wherein the photoconductive switch is arranged for: substantially insulating the deflection unit from the electrical driving circuit, and for conductively connecting the deflection unit to the electrical driving circuit only when said photoconductive switch is illuminated by a light beam.