Magnetic electron lens and elctron microscope using the same

A magnetic electron lens comprising:

• a first magnetic field generating coil made of a superconductor;
• a second magnetic field generating coil made of a superconductor and positioned under said first magnetic field generating coil in a propagating direction of a charged particle beam;
• a first magnetic shielding plate made of a superconductor and disposed above said first magnetic field generating coil so as to enclose an upper side of said first magnetic field generating coil;
• and
• a second magnetic shielding plate made of a superconductor and disposed under said second magnetic field generating coil so as to enclose a lower side of said second magnetic field generating coil;
• wherein said first magnetic shielding plate shields the magnetic field generated above said first magnetic field generating coil and said second magnetic shielding plate shields the magnetic field generated under said second magnetic field generating coil, such that a valley-shaped magnetic field distribution is obtained along a propagation path of said charged particle beam as defined between said first magnetic shielding plate and said second magnetic shielding plate.

A magnetic electron lens comprising:

• a first magnetic field generating coil made of a superconductor;
• a second magnetic field generating coil made of a superconductor and positioned under said first magnetic field generating coil in a propagating direction of a charged particle beam;
• a first magnetic shielding plate made of a superconductor and disposed above said first magnetic field generating coil so as to enclose a part of an upper side of said first magnetic field generating coil;
• and
• a second magnetic shielding plate made of a superconductor and disposed under said second magnetic field generating coil so as to enclose a lower side of said second magnetic field generating coil;
• wherein said second magnetic shielding plate shields a magnetic field generated under said second magnetic field generating coil, such that a valley-shaped magnetic field distribution is obtained in the portion between said first and second magnetic field generating coils.

A magnetic electron lens comprising:

• a first field generating coil made of a paramagnetic material;
• a second magnetic field generating coil made of a superconductor and positioned under said first magnetic field generating coil in a propagating direction of a charged particle beam;
• a first magnetic shielding plate made of a para-magnetic material and disposed above said first magnetic field generating coil so as to enclose a part of an upper side of said first magnetic field generating coil;
• and
• a second magnetic shielding plate made of a superconductor and disposed under said second magnetic field generating coil so as to enclose a lower side of said second magnetic field generating coil,
• wherein said second magnetic shielding plate shields a magnetic field generated under said second magnetic field generating coil, such that a valley-shaped magnetic field distribution is obtained in the portion between said first and said second magnetic field generating coils.