Patent Number: 058959190
Section: claims

1. Gun lens (1, 1', 1") for generating a particle beam with a cathode (2),  an extraction electrode (3),  an anode (4)  and a condenser lens (5),  a) a gun lens (1, 1', 1") for generating a particle beam with  b) a beam blanking system (9) for blanking the particle beam, 2. Gun lens as claimed in claim 1, characterised in that the anode (4) is at ground potential. 3. Gun lens as claimed in claim 1, characterised in that the particles emitted on the cathode (2) are decelerated to a final energy of less than 3 keV in the deceleration field between the extraction electrode (3) and the anode (4). 4. Gun lens as claimed in claim 1, characterised in that the condenser lens (5) is constructed as a single-pole lens. 5. Gun lens as claimed in in claim 1, characterised in that the cathode (2) is formed by a field emission cathode. 6. Gun lens as claimed in claim 1, characterised in that the cathode (2) is formed by a thermal field emission cathode which is superimposed with a suppressor electrode (7). 7. Gun lens as claimed in claim 1, characterised in that the cathode (2) is formed by a photocathode. 8. Gun lens as claimed in claim 1, characterised in that an element (8, 8') made from magnetic material is provided in order to influence the magnetic field produced by the condenser lens (5) in the region of the cathode. 9. Gun lens as claimed in claim 8, characterised in that the condenser lens (5) has an iron circuit (5a) which is coupled to the element (8) made from magnetic material. 10. Gun lens as claimed in claim 8, characterised in that the condenser lens (5) has an iron circuit (5a) which forms an air gap with the element (8) made from magnetic material. 11. Gun lens as claimed in claim 8, characterised in that the element (8, 8') made from magnetic material is disposed between the cathode (2) and the extraction electrode (3). 12. Gun lens as claimed in claim 8, characterised in that the element (8) made from magnetic material is formed by the extraction electrode (3). 13. Gun lens as claimed in claim 8, characterised in that the element (8) made from magnetic material is disposed in the region of the extraction electrode (3). 14. Particle beam device with 15. Particle beam device as claimed in claim 14, characterised in that the gun lens (1, 1', 1") produces a beam crossover in the beam blanking system (9).