| 摘要 |
PURPOSE:To eliminate the effect of extrusion of the electrostatic field by arranging a plurality of detectors symmetrically with a sample placed in the center. CONSTITUTION:An absorption electrode 12 is fitted below an objective lens 2, and the positive voltage is applied to the absorption electrode 12. This voltage generates a vertical electrostatic field on the surface of a sample 3 so as to accelerate the emission of secondary electrons 6 from the sample 3. At least two secondary electron detectors 7 are provided symmetrically, and even numbers of detectors prevent the lateral electrostatic field from becomming asymmetric. The output of detectors 7 can be added, or the output of only one side detector can be used as the intensity modulation signal of a CRT. |
