Eucentric height and your scanning/transmission electron microscope
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- เผยแพร่เมื่อ 20 ส.ค. 2019
- Being able to properly set eucentric height when performing S/TEM is critical to ensuring the best possible instrument performance, but just what is eucentric height anyway and why is it so darn important? This video tackles these questions while also demonstrating how to properly set eucentric height on your S/TEM.
Thanks for watching! Please like, subscribe, and share and let me know if you have any questions or comments. Video topic requests are always welcome and appreciated; I enjoy making these videos and wish I could make them more frequently, but the demands of my job make it tough to do so; I’m in charge of 3 S/TEMs, 2 dual beam FIB/SEM systems, and 1 SEM and this keeps me very busy!
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ngr@ufl.edu - วิทยาศาสตร์และเทคโนโลยี
Definitely one of the most informative electron microscope channels on TH-cam. Your work in much appreciated :D
Thank you!
Hi thank you for the wonderful video. Could you make a video on correcting objective astigmatism.
You're welcome; please take a look at my video on high-resolution imaging, I go over objective astigmatism correction in there.
Thank you, Nicholas! I am the guy ask you about the difference between TEM and STEM mode. So, from this video, when we've adjusted the eucentric focus in TEM mode. It indicates the specimen is now at eucentric height, right? Then when switching to STEM mode, we only adjust Focus Knob to get clear image, and reset Defocus (R2 button), right? after that, if we change beta tilt, the z-position may also be changed, and then we use Z-button to adjust the image quality, right?
Yes, that is correct; if you set eucentric in TEM mode and then switch to STEM, you just need to focus the image, not adjust specimen height; the image should stay basically focused if you only adjust alpha, but if you adjust beta the sample will no longer be eucentric and then you would need to refocus by adjusting z.
How does the STEM make images for the defocus, because the whole system is fixed(expecially, focus are fixed for all the lens). When we adjsut the defoucs distance, the specimen position in the polepiece changs, does that main the sapmle is no longer at the eucentric height anymore? But why we can still get clear image with bigger FOV under defocus?
Sorry， I understand now. Defous images are Shadow Images, not high resolution images. It shouldn't be on the eucentric height.
Thank you for the great video. What settings of the microscope are changed (atlernated) when alpha wobbler is on?
Hi V S: sorry for the late response; the alpha wobbler simply tilts the stage back and forth between plus and minus some set number using the alpha tilt control of the stage, so nothing too complicated.
@@NicholasRudawski Thank you!
Hi. I was wondering how to set the Eucentric Focus value if I found that the Eucentric Focus value is way out of the eucentric height. Thank you!
@biaoyuan3726 you can address this by performing the "Image HM-TEM" alignment from the list of alignments in the alignments panel and then saving an updated (or new) alignment file. I hope this helps.
And if the magnification of objective lens changde, will the operator need to adjust the eucentric again?
Hi Shao: eucentric height does not depend on lens strength, magnification, or mode of operation; it is a parameter of the stage and thus is mechanically constrained.
Good information
Thanks.
I am not able to see the wobble spot in the microscope, how can I adjust it?
Hi Lucia: I'm not sure what you mean here; are you saying you are unable to get the stage tilt to wobble back and forth? What microscope are you using?
@@NicholasRudawski The machine I operated was CD-Stem and the issue I had at that time was the sample failed to center when the program function executed. It was diagnosed as stage issue and it has been fixed by the FEI staff. Thank you for replying.