Jaksch H, Martin J P
Electron Optics Division, Carl Zeiss, D-73446, Oberkochen, Germany.
Anal Bioanal Chem. 1995 Oct;353(3-4):378-82. doi: 10.1007/s0021653530378.
A novel design concept for the electron optical column has been implemented in the realization of a new ultra-high performance SEM. A compound magnetic/ electrostatic objective lens is at the heart of the high-performance column: the imaging aberrations of this new lens type decrease with decreasing beam energy. Any beam cross-over between the electron source (Schottky FE-gun) and the sample has been eliminated in order to avoid broadening of the beam energy spread (Boersch effect). A high beam energy is maintained throughout the column regardless of the electron probe energy selected by the operator. This protects the beam against the effect of stray fields and minimizes any loss of beam brigthness due to stochastic electron-electron interactions. The new SEM achieves outstanding resolution, particularly at the low beam energies (3 nm achievable at E(PE) = 1 keV). The secondary electrons emitted by the sample are detected with very high efficiency by an internal annular detector situated above the final lens. Due to the low imaging aberration level, a high current can easily be focused in a very small probe, thus making the new SEM ideally suited for high-resolution, quantitative X-ray analysis.
一种用于电子光学柱的新颖设计理念已在新型超高性能扫描电子显微镜（SEM）的实现中得以应用。复合磁/静电物镜是高性能柱体的核心：这种新型透镜类型的成像像差会随着束流能量的降低而减小。为避免束流能量展宽（博尔施效应），已消除电子源（肖特基场发射枪）与样品之间的任何束流交叉。无论操作员选择何种电子探针能量，整个柱体中都能保持高束流能量。这可保护束流免受杂散场的影响，并将随机电子 - 电子相互作用导致的束流亮度损失降至最低。新型扫描电子显微镜实现了出色的分辨率，尤其是在低束流能量下（在E(PE)=1 keV时可达到3 nm）。样品发射的二次电子由位于末级透镜上方的内部环形探测器以非常高的效率进行检测。由于成像像差水平较低，高电流能够轻松聚焦在非常小的探针中，从而使新型扫描电子显微镜非常适合进行高分辨率的定量X射线分析。
