Tecnai on-line help manual -- Alignments - UT Southwestern

<strong>Tecnai</strong> on-line help Alignments 72<strong>Tecnai</strong> 12 Software version 2ProcedureThe alignment procedure consists of three steps :• A preparation step for setting up the image in EFTEM mode.• Two steps in which the X and Y pivot points are aligned.The preparation here does not contain a step for the normal mode, because it is assumed that that hasalready been done for the SA pivot points.DescriptionThe alignment of the pivot points of the image deflection coils is essential to the proper functioning ofmany other alignments and calibrations: image shifts, diffraction shifts, detector alignments andmeasurement functions.The image coils pivot points (image shift and diffraction shift) alignment is reasonably insensitive to theoperating conditions and normally needs to be done only once. It is important that the image coils pivotpoints are aligned prior to aligning other parts of the microscope where the image coils are used,otherwise the latter alignments may have to be redone. Alignments where the image coils are used arethose where images or diffraction patterns are moved (image shift, diffraction shift/diffraction alignment).For images displaying the effect of the alignment, see section 6.3.14.5 HM-EFTEM Mi Diffraction-shift pivot pointsPurpose: Align the diffraction shift pivot point = make sure the image does not move when the diffractionshift is changed.Importance: ESSENTIAL for the proper functioning of image and diffraction shifts and the cross-overcorrection.Method: Minimize the movement of the image. The microscope 'wobbles' the diffraction shift whichshould cause no image shift.A common consequence of a diffraction shift that has not been aligned is a mismatch between the imagedetail selected with the selected area aperture and the area actually contributing to the diffractionpattern. When the image coils have not been aligned properly, image and diffraction shift are notuncoupled and the diffraction shift will also cause an image shift, thereby moving the image detail out ofthe selected area aperture. In EFTEM a misaligned diffraction shift will lead to an apparent image shiftwhen the cross-over correction is changed.ProcedureThe alignment procedure consists of three steps :• A preparation step for setting up the image in EFTEM mode.• Two steps in which the X and Y pivot points are aligned.The preparation here does not contain a step for the normal mode, because it is assumed that that hasalready been done for the SA pivot points.DescriptionThe alignment of the pivot points of the image deflection coils is essential to the proper functioning ofmany other alignments and calibrations: image shifts, diffraction shifts, detector alignments andmeasurement functions.The image coils pivot points (image shift and diffraction shift) alignment is reasonably insensitive to theoperating conditions and normally needs to be done only once. It is important that the image coils pivotpoints are aligned prior to aligning other parts of the microscope where the image coils are used,otherwise the latter alignments may have to be redone. Alignments where the image coils are used arethose where images or diffraction patterns are moved (image shift, diffraction shift/diffraction alignment).