ELECTRON MICROSCOPE

摘要

An electron microscope includes an electron beam source, a first electromagnet, a second electromagnet and a detector. The field generated by the first electromagnet has an effect of three lenses subsequently arranged along the beam path. A first lens of these lenses is arranged upstream of the object plane and focuses the beam at the object plane. The second lens of these three lenses is arranged downstream of the object plane. The third lens of these three lenses generates an image of a diffraction plane of the second lens at the detector. The magnetic field generated by the second electromagnet has an effect of a fourth lens and can be changed in order to change a size of the image of the diffraction plane of the second lens on the detector.

主权项

1. An electron microscope, comprising:
an electron beam source configured to generate a beam of electrons having a predetermined kinetic energy; a detector arranged in a beam path of the beam; a first electromagnet arranged along the beam path between the electron beam source and the detector, the first electromagnet configured to produce a magnetic field; a second electromagnet arranged along the beam path between the first electromagnet and the detector, the first electromagnet configured to produce a magnetic field; a current supply configured to supply an adjustable excitation current to the first electromagnet and to supply an adjustable excitation current to the second electromagnet; wherein:
an object plane of the electron microscope is arranged within the magnetic field which generated by the first electromagnet;the object plane is along the beam path relative to the first electromagnet;the current supply is adjustable so that the magnetic field generated by the first electromagnet has an effect on the beam of three electron-optical lenses traversed by the beam;a first lens of the three electron-optical lenses is arranged along the beam path upstream of the object plane;the first lens is configured to focus the beam of electrons at the object plane;a second lens of the three electron-optical lenses is arranged along the beam path downstream of the object plane;the second lens has a diffraction plane;the third lens of the three electron-optical lenses is arranged along the beam path downstream of the second lens;the third lens is configured to generate an image of the diffraction plane of the second lens at the detector;the magnetic field which generated by the second electromagnet has, on the beam, an effect of a fourth electron-optical lens; andthe current supply is configured to change a size of the image of the diffraction plane of the second lens at the detector by changing the excitation current supplied to the second electromagnet.