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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,

Yes, most of the above comments are helpful.  Make sure that you have good conductivity as much as you can. If you are using conductive carbon tape to secure your sample, you can add some silver/carbon paint at the edge of the sample to provide better conductivity.  You can even use the 0.5kV on Hitachi s-4800. This is the beauty of the s-4800.  Not only that, you can change the beam current.  Most of the time Ie=15-20mA are used.  However, for your samplle, I will recommend that you can even reduce to 2-5mA to reduce the beam current/heat to avoid overheat/shift your sample.  Lower down the working distance (WD) will give you better resolution.

One more thing, you can change the pixels of the photo to enhance the image quality (1280 button vs 2560 button).

After saying all of these, I would say the most important issues are the alignment and astigmatism control.  You might think you already adjusted the stigmators correctly but they are not. After adjusting the focus, you need to go back to adjust the stigmators again, back and forth between the "focus and stigmators-x, y" a few times.  If everything is correct, you will suddenly see a focused image since the stigmators are perfect.

Give me your e-mail address I can provide you a brief outline of the operating procedures on s-4800.  I think it will help you in the long run if you just started to learn how to use the s-4800.  Good luck.