Tuning Titan
Goal:
- We use SerialEM for coma-free alignment and objective stigmation.
- Zemlin tableau has to be done with the exact same beam size that will be used for data acquisition!
- Zemlin tableau has to be done without objective aperture to allow a large beam tilt angle to be used (10 mrad).
- Insert objective aperture, this causes some astigmatism as nothing is really non-magnetic..
- Correct astigmatism with SerialEM.
DO NOT CHANGE BEAM SIZE OR MAGNIFICATION!!!
Make sure the AutoLoader turbo is switched off:
AutoLoader, Options flapout, Turbo Auto Off.
SerialEM
- In the Navigator window, go to a carbon area.
- With Low Dose on, Tasks menu, run Eucentric Rough to set the stage height.
- Take a Preview image.
- Switch off SerialEM LowDose.
Titan UI:
- Objective aperture retracted, Objective grey means retracted.
SerialEM:
- Set spot size to 2.
- Lower the screen to burn the carbon area for one minute so it is clean.
- Set spot size 7, raise screen.
Tuning:
- Edit macro 9 TuneScope, defocus -2.5 works for high mags.
For lamellae use higher defocus (e.g. -8 um) and be sure to be on a
thin part of lamella (close to edge)!
- The script sets focus to zero, sets stage height to get the required defocus, stigmates and runs the Zemlin tableau.
- Check if the Thon-ring fits look reasonable!!!! Drop spot size if more dose is needed.
- Start script 9.
-
Just to be sure, objective aperture needs to be out, if so, click yes.
- When Zemlin tableau is done, this message pops up, don't click anything yet!
The script has switched to Diffration mode and lowers the screen, so check the microspe pc.
Titan UI:
- Insert 100 micron objective aperture by clicking the Objective button, yellow means inserted.
- Click in the FluCam viewer and scroll the mouse wheel up until you see the aperture around the beam.
NOTE: there should be some carbon and or ice in the beam, otherwise you do not see the white disk at all!
- Click Adjust (next to Objective) in the Aperture control panel, use multi function buttons to center.
- De-select Adjust in Aperture control panel.
SerialEM:
- Click Yes to continue:
- Image will be stigmated with the objective aperture in.
- When done close the FFT window in SerialEM.
DONE!
Switch on SerialEM LowDose.