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Modification Of a Conventional TEM (CTEM) for Lorentz Microscopy

Published online by Cambridge University Press:  02 July 2020

M. Wall
Affiliation:
Advanced Microtechnology Program, Livermore National Laboratory, Livermore, CA, 94550
S. Bajt
Affiliation:
Advanced Microtechnology Program, Livermore National Laboratory, Livermore, CA, 94550
C. Cerjan
Affiliation:
Advanced Microtechnology Program, Livermore National Laboratory, Livermore, CA, 94550
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Extract

We have modified a CTEM in order to perform Lorentz microscopy experiments at high magnification and resolution on magnetic materials. The modification consists of the adaptation of a second side entry goniometer (SEG) to the CTEM (JEOL 200CX STEM) column above the objective lens, in a region of the column where the measured residual magnetic fields are < 0.5 Gauss with the objective lens in a fully excited state (see Figure 1).

With the specimen positioned above the objective lens, it is necessary to increase the excitation of the lens by approximately 20% in order to bring the image into focus. This combination of a specimen positioned above the object pole piece, and the higher objective lens excitation, affects several changes in the optics. First, if a specimen is positioned within the pole piece gap and the objective lens is turned off for Lorentz microscopy purposes, the highest typical magnification achievable is approximately 1,000 X and the resolution is not much better than 0.1μm.

Type
Advances in Instrumentation and Performance
Copyright
Copyright © Microscopy Society of America

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References

1.Chapman, J. N., J. Phys. D Appl. Phys., 17(1984)623.CrossRefGoogle Scholar
2.Dooley, J. and DeGraef, M., Ultramicroscopy, 67(1997)113.Google Scholar
3. This work was performed under the auspices of the US Department of Energy by the Lawrence Livermore National Laboratory under contract W-7405-Eng-48. The authors wish to thank Richard Gross and Dane Ceiley for their technical support of this project.Google Scholar