| 摘要 |
<p>An electon-optical device comprises a magnetic circuit (1) which is shaped as a closed coil and is made of a ferromagnetic material having a good magnetic permeability, the magnetic circuit (1) including an internal core (2), an external lateral part (3) and butt-end jaws (4, 5). The inner hollow of the magnetic circuit (1) houses an exciting winding (13) which encircles the internal core (2) and which is common for all the electromagnetic lenses of the device. The inner core (2) of the magnetic circuit (1), being also common for all the electromagnetic lenses of the device, is shaped as an elongated hollow cylinder provided with annular grooves (16) on its outer surface. The annular grooves (16), together with the adjacent parts of the inner core (2) placed on both sides of each of the annular grooves (16), are forming the poles of the electromagnetic lenses, the number of which is equal to that of the electromagnetic lenses in the device. </p> |
