| 摘要 |
PURPOSE:To switch an observation mode between a transmission image and a scanning image by varying the intensity of a front magnetic field lens while maintaining the state of excitation in which a transmission image is formed by the back magnetic field lens of an objective according to electron rays transmitted by a sample. CONSTITUTION:A magnetic piece 4 is attached to the upper part of a yoke 3 for introducing a magnetic flux developed from a main coil 1. A magnetic piece 5 is placed under the magnetic piece with a gap (G1) provided between them. It is supported by a spacer 6 and provided with a hole 8 into which a ferromagnetic sample 7 is inserted. A magnetic piece 9 is attached inside the yoke 3 facing the magnetic piece 5 with a gap (G2) provided between the magnetic pieces 5 and 9. In addition, an auxiliary coil 10, which is excited with a lens power source 11, is attached to the upper part of the yoke 3. A magnetic piece 12 is attached around the coil 10. Owing to the above constitution, a front magnetic field lens 13a can be formed by the magnetic field of the gap (G1) and a back magnetic field lens 13b can be formed by that of the gap (G2). Besides an observation mode can be switched between a transmission image and a scanning image through the controlling of the intensities of the lenses 13a and 13b. |
