| 摘要 |
An electronic optics device with variable illumination and aperture limitation is provided including, between a particle source and an object an image of which it is desired to project in an image plane, a set of three lenses with electronically controllable focal lengths, the first one being situated as close as possible to the source and associated, in its main plane or in the vicinity of this plane, with an aperture limitation diaphragm, the object being placed in the main plane of the third lens or in the vicinity thereof, the focal length of these three lenses being controlled so as to give to the section of the electronic beam in the object plane a value determining the desired illumination and to the image of the diaphragm a diameter and a position determining the desired aperture of the beam.
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