| 摘要 |
PURPOSE:To make control at the change-over of observation mode unnecessary by increasing the thickness of the root of the second magnetic piece of an objective, which is constituted by providing an yoke with the first to the third magnetic pieces, and forming an annular concave area near the pointed end of the second magnetic piece. CONSTITUTION:After magnetic pieces 2, 3 and 4 are attached to a yoke 1, a coil 5 for forming a first lens magnetic field between the magnetic pieces 2 and 3 is connected to a power supply 6 through a change-over device 7 and a coil 8 for forming a second lens magnetic field between the magnetic pieces 3 and 4 is connected to a power supply 9. The thickness of the root (T2) of the second magnetic piece 3 is made larger than the thickness of the pointed end (T1). Next, an annular concave area (U) is formed on an area of the third-magnetic- piece-4-side surface near the pointed end of the second magnetic piece 3, thereby forming an objective lens which is then combined with a sample slanting device. Therefore, when a change-over switch 7 is switched to modes for transmitted-image observation and converged-electron-ray diffraction, any magnetic saturation of the second magnetic piece 3 is not caused and it is not necessary to control the excitation current every time when the switching is performed. |
