Apparatus and method for detecting one or more scanning charged particle beams

A method for inspecting a sample, wherein the method comprises the steps of:

• arranging the sample in a sample holder,
• generating and directing one or more primary charged particle beams towards the sample using a charged particle column,
• wherein said charged particle column focuses said one or more primary charged particle beams at one or more charged particle beam spots onto the sample,
• wherein photons are created by said one or more focused primary charged particle beams when said one or more primary charged particle beams impinge on the sample or when said one or more primary charged particle beams impinge onto a layer of luminescent material after transmission of said one or more primary charged particle beams through the sample,
• projecting or imaging at least part of said photons from said one or more charged particle beam spots along an optical beam path onto one or more light spots on a photon detector using an optical assembly, wherein the optical assembly comprises a mirror or a polygon mirror arranged in the optical beam path between the sample holder and the photon detector, wherein the mirror or the polygon mirror is configured for reflecting the optical beam path at a deflection angle between 0 and 180 degrees,
• detecting photons using the photon detector, and
• scanning the one or more primary charged particle beams over the sample in a scanning direction using a scanning unit, and shifting the one or more light spots and/or the photon detector with respect to each other using a shifting unit, wherein the shifting unit comprises a mirror actuator which is configured for adjusting a tilting angle of the mirror or a rotating actuator which is configured for rotating the polygon mirror,
• wherein said shifting unit at least partially compensates a movement of the one or more primary charged particle beams on the sample or on the layer of luminescent material due to the scanning of the one or more primary charged particle beams by the scanning unit and compensates the movement of the one or more primary charged particle beams so that the one or more light spots substantially remain at the same position on the photon detector during the scanning of the one or more primary charged particle beams by the scanning unit.