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

<strong>Tecnai</strong> on-line help Alignments 50<strong>Tecnai</strong> 12 Software version 2ProcedureThe alignment procedure consists of two steps:• In the first step the beam is shifted to the center of the screen. For this purpose the alignment valueis used while the user value is reset to zero.• In the second step, the direction of the beam shift is aligned with respect to the movement by thetrackball. When the trackball is moved from left to right, the beam should also move from left to righton the screen. If the beam moves in a different direction, adjust the direction with the Multifunction Yknob.DescriptionThe beam shift has two components, an alignment value and a variable 'user' value. If properly aligned,the alignment value will have the beam centered on the screen. It then is only necessary to reset the'user' value to zero to have the beam back at the screen center.The alignment value for the beam shift is used frequently in alignment (any time the beam must becentered with Multifunction X,Y). In any such step, the 'user' value of the beam shift is always reset tozero. Therefore, on a properly aligned microscope, it is always possible to find the beam again simply byentering this alignment step: the 'user' value is reset to zero, so the beam should now be centered.9.8 Beam shift calibration NanoprobePurpose: Calibrate the beam shift to physically meaningful values.Importance: CONVENIENCE.Method: Move the focused beam to the edge of the viewing screen and adjust the displayed value of theimage shift using Multifunction Y.ProcedureThe alignment procedure consists of four steps:• In the first step the beam is accurately centered on the screen.• In the second step, the beam is shifted with Multifunction X to the edge of the viewing screen (thearea where the fluorescent material - yellow/green - stops and the aluminium substrate is visible).Then the displayed value for the beam shift is adjusted to the correct value with the Multifunction Y.• The third and fourth steps repeat the first and second steps but now for the Y direction of the beamshift.9.9 Beam tilt (dark field) calibration NanoprobePurpose: Calibrate the beam tilt (dark field) to physically meaningful values.Importance: ESSENTIAL for meaningful beam tilt values in dark field.Method: Tilt the beam and adjust the displayed value of the beam tilt using Multifunction X,Y.ProcedureThe alignment procedure consists of five steps:• The first step is a preparation step for the diffraction mode.• In the second step the diffraction pattern must be centered accurately (on the center of the viewingscreen or the tip of the beam stop).• In the third step, the beam is tilted (this is, the diffraction pattern is shifted) with Multifunction X tobring a ring to the center and the beam tilt value is adjusted with Multifunction Y to the correct value.• The fourth and fifth steps repeat the procedure of the second and third steps for the Y diffractionshift.