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

<strong>Tecnai</strong> on-line help Alignments 55<strong>Tecnai</strong> 12 Software version 2The procedure follows these steps:• A preparation step in which the HM image is focused.• The current through the stigmator is wobbled in the X direction and the operator minimizes imagemovement.• The same is done for the Y direction.The stigmator current wobble will result in two images, which will overlap when the stigmators arealigned correctly. It is advisable to use a specimen with relatively large, easily recognized image detail.Misaligned objective stigmator.Aligned objective stigmator.11.3 Diffraction stigmator calibrationThe microscope contains a diffraction stigmator to correct for astigmatism in HM diffraction and LMimage. When this stigmator is misaligned, adjustment of the stigmator setting will lead to an apparentHM diffraction shift / LM image shift. When the stigmator is aligned correctly, these shifts arecompensated by an identical but opposite shift - this time using the image deflection coils. In order toalign the stigmator, it is necessary to determine the relation between a change in stigmator setting andthe LM image shift. This relation is determined in the procedure for aligning the stigmator.The procedure follows these steps:• A preparation step in which the microscope is switched to LM and the image is focused.• The current through the stigmator is wobbled in the X direction and the operator minimizes imagemovement.• The same is done for the Y direction.The stigmator current wobble will result in two images, which will overlap when the stigmators arealigned correctly. It is advisable to use a specimen with relatively large, easily recognized image detail.