Focusing and positioning device for a particle-optical raster microscope

A particle beam system comprising:

• an objective lens defining a particle-optical beam axis;
• a particle beam generator for generating a particle beam for travel along said particle-optical beam axis;
• a specimen chamber;
• an object table for accommodating an object thereon and said object table being mounted in said specimen chamber;
• a focusing and positioning ancillary device including:
• 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.

A method of focusing and positioning an object in a particle-optical raster microscope including an objective defining a particle-optical beam axis and an object table, said method comprising the steps of:

• (a) providing a light beam having a predetermined wavelength and intersecting said particle-optical beam axis at a predefined position;
• (b) providing a camera sensitive to said wavelength;
• (c) providing a display whereon the position of said particle-optical beam axis is marked with a line-shaped marking;
• (d) recording an image of said object positioned on said object table via said camera;
• (e) positioning said object table in the direction of said particle-optical beam axis until said light beam intersects said object on said line-shaped marking in the image of said object shown on said display with said line-shaped marking extending longer in length in the direction of said particle-optical axis than perpendicular to said particle-optical beam axis;
• and,
• (f) switching over said particle-optical raster microscope for irradiation of said object with electrons and displaying an image of said object via detected particles or light quanta generated by said irradiation of said object with charged particles.