Basic Alignment of Tecnai F30

1
Basic Alignment of Tecnai F30

• Yan Cao
• Sept. 9th 2002
• Case Western Reserve University

2
Before Starting

• Check the vacuum (gun  1, column lt 20)
• Remove the objective aperture
• Refill liquid N2 (turn away the monitor)
• DO NOT spill N2 on the glass of the viewing
  chamber

3
Inserting the Specimen Holder

• Select the appropriate holder, click return
• Make good connection with ?-tilt cable
• Hear the tilt motors reset the ?-tilt
• Push the holder into column carefully
• Check the vacuum, open V4 and V7

4
Abnormal Behavior

• Do not insert the holder into the column
• Switch off the turbo pump (7 min down)
• Make sure V41 and V8 are closed
• Reset the holder and Remove it
• NEVER shut off the computer

5
Condenser Aperture (C1 C2)

• Aperture sizes influence coherence convergence,
  spot size and total current
• Make the beam stay centered on the screen
• Ensure the reproducible illuminating conditions
• Misalignment leads to a beam tilt

6
FEG TEM-BF Mode

• C2 aperture 100/50 ?m
• Objective 100 ?m
• Extractor 3.5 ? 4 kv
• Emission lt 100 mA
• Gun Lens 1-3
• Spot size 1
• Magnification 500 k 750k

7
FEG EDX Nanoprobe Mode

• C1 aperture 30 ?m
• C2 aperture 150 ?m
• Objective No
• Extractor lt 4.6 kv (i.e. crossover mode)
• Gun Lens 5-8 (depending on current)
• Spot size 5
• Do not change saved FEG registers

8
Alignment Procedure

• Eucentric focus
• Gun alignment / condenser stigmator
• Beam tilt pivot point
• Rotation center
• Coma-free pivot point
• Coma-free alignment

9
Eucentric Focus

• Importance
• Area of interest stays centered when tilting
• Defines the reference value for the
  objective-lens current
• Procedure
• Press Eucentric focus button to set the objective
  lens at eucentric height
• Press wobbler button, focus specimen by adjusting
  z height, not focus

10

• a. Focus without use of the wobbler
• b. Focus after use of the wobbler

11

• c. Out of focus - wobbler in chosen direction.
• d. Out of focus - wobbler perpendicular to c.

12
Alignment Procedure

• Eucentric focus
• Gun alignment / condenser stigmator
• Beam tilt pivot point
• Rotation center
• Coma-free pivot point
• Coma-free alignment

13
Gun tilt beam comes down parallel to the optical
axis Gun shift beam comes down along the optical
axis
14
Condenser Stigmator

• Purpose
• Correct for beam astigmatism
• Determine the relation between a change in
  stigmator setting and the beam shift
• Misalignment lead to a beam shift
• Procedure
• Focus the beam (not completely).
• The current through the stigmator is wobbled in
  the x or y direction. Minimize beam movement

15
Condenser Stigmator
Misaligned
Aligned
16
Alignment Procedure

• Eucentric focus
• Gun alignment / condenser stigmator
• Beam tilt pivot point
• Rotation center
• Coma-free pivot point
• Coma-free alignment

17
Beam Tilt Pivot Point

• Purpose
• Make sure the beam does not shift when tilted
• Keep beam centered during rotation-center
  alignment, focusing with the wobbler and DF
• Procedure
• Set up the image.
• Align x or y pivot points, until a tilting beam
  remain centered on the specimen, giving no beam
  shift

18
Alignment Procedure

• Eucentric focus
• Gun alignment / condenser stigmator
• Beam tilt pivot point
• Rotation center
• Coma-free pivot point
• Coma-free alignment

19
Rotation Center

• Purpose
• Ensure the beam is along the optical axis of the
  objective lens
• Minimizing lens aberrations and image movement
  during focusing
• Procedure
• Wobble the objective lens current. Image go
  through focus
• Align the rotation center to minimize the
  movement of the image
• Based on beam tilt. Beam alignment procedure.

20
Alignment Procedure

• Eucentric focus
• Gun alignment / condenser stigmator
• Beam tilt pivot point
• Rotation center
• Coma-free pivot point
• Coma-free alignment

21
Coma-free Pivot Points

• Purpose
• Ensure the beam stays well-centered while
  wobbling
• Obtaining reliable and accurate coma-free
  alignment
• Procedure
• Center the beam and focus the image.
• The beam is wobbled in x or y directions. Adjust
  coma-free pivot point until the two wobbling
  beams overlap. Minimize the movement

22
Alignment Procedure

• Eucentric focus
• Gun alignment / condenser stigmator
• Beam tilt pivot point
• Rotation center
• Coma-free pivot point
• Coma-free alignment

23
Coma-free Alignment

• Purpose
• Ensure the beam along optical axis of the
  objective lens
• Obtaining reliable and accurate high-resolution
  data
• Procedure
• Center the beam and focus the image
• The beam is wobbled in the x or y direction with
  a set amount of beam tilt. Adjust the coma-free
  center until two wobble images have the same
  defocus.

24

• Do not save settings in Filter Control
• Do not overexpose the CCD
• Familiar with the button for manually closing V7
  (in case of vacuum emergency)
• Do not save your experimental data to microscope
  computer, but the black dell
• Never stop an XEDS or EELS in STEM mode

25
Thanks for your attention!Any question?