Alignment

The beam travels from the electron gun at the top through the sample and down to the viewing screen. If it is off axis or suffers from astigmatism then poor imaging can be expected. The path needs to be adjusted depending on viewing parameters. This process is called alignment. TEM alignment procedures involve a number of systems and parts of the instrument:

1. Illumination system: beam tilt; beam shift
2. Condenser aperture alignment
3. Condenser astigmatism correction
4. Alignment of illumination with respect to the objective lens
5. Objective aperture centering
6. Objective astigmatism correction
7. Alignment of intermediate lens

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