Diffraction in TEM

Do not attempt to do anything you have not been trained to do by ePSIC staff.

  1. Wobble objective lens and set CL3 to minimise change in illumination area. This ensures parallel illumination.

  2. Insert a condenser lens aperture of 20um or smaller (CLA2, 4) and centre.

    Never swap to diffraction mode without a small condenser lens aperture inserted

  3. Ensure that area of interest is illuminated and insert a selected area aperture if required.

  4. Ensure phosphor screen is lowered.

  5. Press ‘Diff’ on microscope panel.

  6. Select the required camera length on TEMCentre.

  7. Using the projector lens deflectors move the central spot to the beam stop position (marked on the phosphor screen).

  8. Using the small focus screen, focus the diffraction pattern with diff focus knob. 

    Exposing the small focus screen to the central beam for prolonged periods may damage the screen.

  9. If necessary correct for intermediate lens astigmatism with the IL stig deflectors.

  10. Insert the OneView camera and lift the phosphor screen.

  11. Using the projector lens deflectors mover the central spot so that it is entirely covered by the beam stop.

    Exposing the OneView camera to the central beam for prolonged periods may damage the camera.

  12. Record your diffraction pattern.

  13. Don’t leave the diffraction pattern on the OneView camera for longer than is necessary.

  14. Press ‘Mag’ on the microscope panel to return to imaging mode.