| 摘要 |
833,249. Electron microscopes. PHILIPS ELECTRICAL INDUSTRIES Ltd. Oct. 1, 1956 [Oct. 4, 1955], No. 29852/56. Class 39(1). A magnetic lens for an electron microscope has two sets of auxiliary polepieces, extending from one or each polepiece of the lens, each set being rotatable relative to the other, and both sets being rotatable together, in order to correct astigmatism. In Fig. 2, auxiliary sector pole-pieces 1, 2 overlying main polepiece 7 are rotated with toothed ring 13 by means of a pinion 11. The other set of auxiliary polepieces 3 is rotated on an inner ring (not shown) when engaged by sectors 1, 2. In Fig. 5, the system of Fig. 2 for correcting second-degree astigmatism is mounted on the lower polepiece 25, and a system with six sectors for correcting third-degree astigmatism is mounted on the upper polepiece 24. |
