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一、问题的提出与装置原理扫描电子显微镜的二次电子像的分辨率,对同样的样品来说,主要取决于电子探针的直径,而电子探针的最小直径取决于末级透镜的象差和电子枪的亮度。在电子枪亮度决定之后,就取决于末级透镜的象差。它主要由球面象差、色差以及象散组成。存现代的技术条件下,对于球面象差来说可使色差和象散减少到可忽略的程度。因此,分辨率主要取决于末级透镜的球面象差的大小。目前减少磁透镜的球面象差的
I. PROBLEM PROBLEMS AND DEVICE PRINCIPLE The resolution of a secondary electron image of a scanning electron microscope depends mainly on the diameter of the electron probe for the same sample and the minimum diameter of the electron probe depends on the image of the final lens Poor and electron gun brightness. After the brightness of the electron gun is decided, it depends on the aberration of the last lens. It is mainly composed of spherical aberration, color difference and astigmatism. With the modern technology, spherical aberration can reduce the color aberration and astigmatism to a negligible extent. Therefore, the resolution depends mainly on the size of the spherical aberration of the final lens. Currently reducing the spherical aberration of the magnetic lens