Patent ID: 7888643

Claim:
A focusing and positioning ancillary device for a particle-optical raster microscope having an objective defining a particle-optical beam axis and an object table for accommodating an object thereon, the focusing and positioning ancillary device comprising: an illuminating unit configured to generate at least one of a collimated light beam and a focused light beam at a first angle to said particle-optical beam axis with said light beam having a wavelength and intercepting said particle-optical beam axis at a predefined position; a camera sensitive to said wavelength and configured to record an image of said object positioned on said object table at a second angle relative to said particle-optical beam axis; a display; a control unit configured to cause said image recorded by said camera to be shown on said display together with a line-shaped marking indicating the position of said particle-optical beam axis in said image; and, said line-shaped marking being displayed in said image on said display showing said line-shaped marking extending longer in length in the direction of said particle-optical axis than perpendicular to said particle-optical beam axis.