Particle source with selectable beam current and energy spread
View Patent ↗The invention describes a particle source in which energy selection occurs. The energy selection occurs by sending a beam of electrically charged particles 13 eccentrically through a lens 6 . As a result of this, energy dispersion will occur in an image 15 formed by the lens 6 . By projecting this image 15 onto a diaphragm 7 , it is possible to only allow particles in a limited portion of the energy spectrum to pass. Consequently, the passed beam 16 will have a reduced energy spread. By adding a deflection unit 10 , this particle beam 16 can be deflected toward the optical axis 2 . One can also elect to deflect a beam 12 going through the middle of the lens 6 —and having, for example, greater current—toward the optical axis.
1. A particle-optical apparatus equipped with a particle source, which particle source is embodied to generate at least one beam of electrically charged particles ( 16 ) and which particle source is provided with:
a particle-emitting surface for emission of the electrically charged particles;
a lens for formation of an image of the particle-emitting surface;
a beam-limiting diaphragm for limitation of said beam of particles, and;
an energy-selecting diaphragm at the location of the image, characterized in that
the beam-limiting diaphragm is embodied in such a way that said beam is a beam that goes through the lens eccentrically.
2. A particle-optical apparatus according to claim 1 , in which the beam-limiting diaphragm is also embodied to allow a beam going through the middle of the lens to pass.
3. A particle-optical apparatus according to claim 1 , provided with a deflection unit, which deflection unit is embodied to deflect one of the beams of electrically charged particles toward an optical axis, in such a manner than this beam further propagates about the optical axis.
4. A particle-optical apparatus according to claim 1 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
5. A particle source for use in a particle-optical apparatus, the particle source configured to generate at least one beam of electrically charged particles, the particle source comprising:
a particle-emitting surface for emission of the electrically charged particles;
a lens for formation of an image of the particle-emitting surface;
a beam-limiting diaphragm for limitation of said beam of particles, the beam-limiting diaphragm is embodied in such a way that said beam is a beam that goes through the lens eccentrically; and
an energy-selecting diaphragm at the location of the image.
6. A particle-optical apparatus according to claim 2 , provided with a deflection unit, which deflection unit is embodied to deflect one of the beams of electrically charged particles toward an optical axis, in such a manner than this beam further propagates about the optical axis.
7. A particle-optical apparatus according to claim 2 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
8. A particle-optical apparatus according to claim 3 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
9. A particle-optical apparatus according to claim 6 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
10. A particle-optical source according to claim 5 , in which the beam-limiting diaphragm is also embodied to allow a beam going through the middle of the lens to pass.
11. A particle-optical source according to claim 5 , provided with a deflection unit, which deflection unit is embodied to deflect one of the beams of electrically charged particles toward an optical axis, in such a manner than this beam further propagates about the optical axis.
12. A particle-optical source according to claim 10 , provided with a deflection unit, which deflection unit is embodied to deflect one of the beams of electrically charged particles toward an optical axis, in such a manner than this beam further propagates about the optical axis.
13. A particle-optical source according to claim 5 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
14. A particle-optical source according to claim 10 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
15. A particle-optical source according to claim 11 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.
16. A particle-optical source according to claim 12 , in which the particle-emitting surface has the form of several, non-juxtaposed, particle-emitting constituent surfaces.