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fe77021

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[交流] 【请教】请教扫描电镜调焦问题已有28人参与

系里面买了一个日立s4800的场发射扫描电镜，按说此仪器很好，能够放到到10万倍应该没有问题。实际情况在放大2万倍左右很方便的拍出图片，可是一旦到5万倍图片就模糊不清楚，10万倍更是拍出图片不能用。在每次聚焦时候图形乱晃动，好像是聚焦不好的样子。现在害的我只能去外校一个最大放到2万倍的地方测扫描。有没有这方面有经验的虫友指教一下，谢谢啊！值得说明的是，我系s4800一般用电压1千伏，外校2万伏。不知道和这个有没有关系。上两张图，帮忙分析一下。这张是我系的：

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wtskjen

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fe77021(金币+1):谢谢 2010-06-10 15:08:50
fe77021(金币+1):谢谢 2010-06-10 15:11:03

If you just start to use this s-4800 recently, please make sure that you have good beam alignment and good stigmators adjustments in the x and y directions. These two are the most critical issues to use the Hitachi s-4800.

When you switch from the “LM” to high magnification (no LM) the beam can shift, you need to center the beam again at high magnification.  Stigamtors and focus knobs will affect each other.  Therefore, you need to adjust them back and forth until the stigmators and focus are properly adjusted.

If your sample does not have a charge problem (too bright or shifting the image) use higher KV to get better depth of field. Your working distance of 8.3 mm should be OK. Just want to remind you that you were using the upper detector only SE(U).  If you adjust everything right, the SE(M) usually gives better image.

Anyway, the beam alignment and astigmatism are the most critical procedcure to operate the s-4800 SEM.  Also, you need to make sure that your beam current is stabilized.  Cold field emission gun needs a little bit time to stabilize. Cheer up!