| 摘要 |
PURPOSE:To enable a contrast image of a phase substance to be observed by installing a phase plate, consisting of an annular magnetic substance having a closed internal rotary magnetic flux, on o near the back focus plane of an objective. CONSTITUTION:In an electron microscope constituted of an electron source 1, a condenser 2, a sample 3, an objective 4, a magnifying-lens system 6 and an observation screen 7, a phase plate 5 consisting of an annular magnetic substance having a closed internal rotary magnetic flux is placed on the back focus plane of the lens 4. Electron rays 8 transmitted by the phase substance 3 and having the same amplitude and phase as those of incident waves, after passing through the lens 4, travel through the inner side of the phase plate 5 thereby undergoing phase shifts. On the other hand, electron rays 9 scattered by the phase substance 3 travel through the outer side of the phase plate 5, thereby enabling a contrast image formed on the observation screen 7 to be observed. The focal distance of the lens 4 is adjusted to cause a magnetic field smaller than the magnetic force resistance of the magnetic substance 5 to be formed by the lens 4. The radius (R) of the phase plate 5 is adjusted according to the relationship R<fXtheta when the focal distance of the lens 4 is supposed to be (f) and the angle of the scattering of electron rays caused by the sample 3 is supposed to be (theta). |
