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

<strong>Tecnai</strong> on-line help Alignments 58<strong>Tecnai</strong> 12 Software version 2Important:• The specimen must be at the eucentric height. To do this properly, go to the Nanoprobe mode andpress the Eucentric Focus button. The objective lens current is now set to the proper value forNanoprobe (provided the SA objective preset has been aligned properly). Then bring the specimeninto focus with the Z height of the specimen stage. (By doing it this way you will attain a morereproducible setting than by using the alpha wobbler.)• During STEM alignment TIA (Tem Imaging & Analysis) must be running.ProcedureThe alignment procedure consists of three steps:• One preparation step for setting up the image.• Two steps in which the X and Y pivot points are aligned.Note: The tilt pivot point set in this subprocedure is the same as the Nanoprobe beam-tilt pivot point.The alignment is repeated here to ensure that the rotation center alignment in STEM can be doneproperly.12.4 HM-STEM Rotation centerPurpose: Make sure that the beam is along the optical axis of the objective lens.Importance: ESSENTIAL for minimizing lens aberrations and image movement during focusing.Method: The microscope 'wobbles' the objective lens current, making the image go through focus. Makethe sideways movement of the image as small as possible with the rotation center (= tilting the beam tothe optical axis).The 'focus wobble' can be made smaller or larger with the FOCUS STEP SIZE knob.Important:• The specimen must be at the eucentric height. To do this properly, go to the Nanoprobe mode andpress the Eucentric Focus button. The objective lens current is now set to the proper value forNanoprobe (provided the SA objective preset has been aligned properly). Then bring the specimeninto focus with the Z height of the specimen stage. (By doing it this way you will attain a morereproducible setting than by using the alpha wobbler.)• During STEM alignment TIA (Tem Imaging & Analysis) must be running.ProcedureThe alignment procedure consists of five steps:• A preparation step in which the beam is focused. The image must be focused by setting thespecimen to the proper eucentric height (by now the eucentric focus for STEM should have beendefined).• A second step in which the beam is (temporarily - for this alignment procedure) defocused.• A third step in which the image movement is minimized.• A fourth step in which the beam is centered and focused.• A fifth step in which the condenser aperture is aligned properly.Note: If the aperture required considerable re-alignment, one should step back through the procedureand repeat from step 2 onwards.