| 摘要 |
<p>A correction system for a high resolution charged particle beam apparatus provided with two hexapoles (2,4) enclosing a telescopic round-lens system (7) with two lenses (8,10) which are arranged so that outer focal points (20,22) of the lenses are coincident with nodal points (16,18) which coincide with centre points of the hexapoles. An additional coma-free round-lens doublet (30) is added for imaging a coma-free plane (50) of a lens (51) to be corrected into a centre plane (16') of a first hexapole (2) of the system. For both round-lens doublets the spacing between the two lenses preferably equals 2f, f being the focal length of each lens. <IMAGE></p> |
