Particle beam apparatus having an annularly-shaped illumination aperture

A particle beam apparatus defining an optical axis and comprising:

• an illuminating system for illuminating an object to be positioned in an object plane with a beam of charged particles which splits into a null beam and higher diffraction orders at said object;
• an objective arranged along said optical axis for imaging said object illuminated by said illuminating system;
• said illuminating system being configured to generate, during operation, an annularly-shaped illuminating aperture in a plane fourier transformed to said object plane;
• said objective having a focal plane facing away from said object plane;
• a phase-shifting element mounted in said focal plane or a plane conjugated thereto;
• said phase-shifting element including an einzel lens having first and second outer electrodes arranged along said optical axis and an inner electrode arranged therebetween;
• said electrodes being arranged and charged with electrical potential, during operation, so as to cause the potential at said optical axis to correspond to the potential at said first and second outer electrodes of said einzel lens;
• wherein said inner electrode comprises a plurality of segments;
• potentials of opposite polarity are applied to respective ones of each two of said segments lying mutually opposite each other with reference to said optical axis;
• and,
• wherein said plurality of segments are electrically insulated from each other.

A particle beam apparatus defining an optical axis and comprising:

• an illuminating system for illuminating an object to be positioned in an object plane with a beam of charged particles which splits into a null beam and higher diffraction orders at said object;
• an objective arranged along said optical axis for imaging said object illuminated by said illuminating system;
• said illuminating system being configured to generate, during operation, an annularly-shaped illuminating aperture in a plane fourier transformed to said object plane;
• said objective having a focal plane facing away from said object plane;
• a phase-shifting element mounted in said focal plane or a plane conjugated thereto;
• said phase-shifting element including a carrier;
• and, an annularly-shaped electrode accommodated in said carrier;
• said annularly-shaped electrode having a side facing away from said optical axis in a radial direction;
• said electrode having an edge on said side thereof;
• said edge and said carrier conjointly defining an annular gap therebetween wherein said phase-shifting element imparts a phase shift to the beam of charged particles split into higher diffraction orders in response to a potential applied thereto;
• and,
• wherein said phase-shifting element does not influence, or only slightly influences, said null beam.