| 摘要 |
This invention relates to a fine focusing lens for charged particle beams. Since the field lines of the poles are additive, and the lens 50 can be made to be very small, the lens can be used inside of a coarse focusing lens 51. The lens 50 employs a plurality of poles 1-32, evenly spaced, circumferentially around the lens. The poles may be wires 38 for electromagnetic poles or plates 35 for electrostatic poles. Each pole can be tagged to induce a frequency, pulse, or phase signal on the charged particle beam 49, so that the effects of each pole on the beam can be separately detected. The beam can therefore be focused by seeing the effects of and adjusting each pole separately. As the number of poles increases, the ability to finely focus a charged particle beam increases. The lens 50 as shown in the figures has 32 poles, which is enough to very finely focus a charged particle beam.
|
