- DP light is on, HIGH VACUUM light is on.
- Ready indicator light is on.
- Objective aperture is out.
- SAD aperture is out.
- Accel Voltage is off (HT button is out).
- Specimen holder is inserted into the goniometer (opening for sample).
- Stage drives are centered
- Shutter on Auto.
- CAMERA AIRLOCK OPEN lit.
- Logged into SUMS on the computer in the room.
I. Select the accelerating voltage for the sample
- Press HT and sequentially increase the accelerating voltage in steps: push in the button for 20kV,
- wait for the dark current to stabilize,
- push in the button for 40kV, wait for the dark current to stabilize,
- push in the button for 60kV, etc.
II. Load your sample into the appropriate sample holder
- Remove the sample holder from the goniometer:
- Hold the handle protruding from the goniometer and pull straight back
- Turn 90o towards you
- Ease the holder out by bracing your thumb against the goniometer, and pulling straight back again
- Avoid touching the sample holder beyond the o-ring; handle your sample with tweezers. Load a holey carbon grid for checking the alignment of the column.
- Rest the loaded sample holder in the airlock until ready to insert.
III. Turn on and increase the current to the filament until the black filament image is visible
- The beam will become visible around 6, and the filament image around 7.
- Turn the knob slowly and at an even rate.
IV. Align the filament image, if needed
- GUN ALIGN TILTS will center the black image with respect to the beam;
- GUN ALIGN TRANS will center the filament image and beam assembly on the screen.
- Saturate the filament when done with the alignment.
V. Align the gun and the condenser lens
- Align the beam at crossover with the center of the screen (GUN ALIGNMENT: TRANS), spot size 1.
- Switch to spot size 3, adjust the CONDENSER knob to crossover,
- center the spot with ALIGNMENT: TRANS knobs (on either side of the column)
- Switch back to spot size 1, adjust to crossover, and
- center with GUN ALIGNMENT: TRANS.
- Repeat until spot centers coincide with the center of the screen.
- Pick a spot size to work with, 1 or 2.
VI. Check for condenser astigmatism
- If the beam is not round at crossover (the smallest diameter), adjust the COND STIG knobs.
VII. Center the condenser aperture
- Spread out the beam on the screen, checking for symmetry in the way it spreads.
- If it is asymmetrical, adjust the aperture drives on the condenser aperture housing.
VIII. Insert the sample holder
- Turn down the filament emission to 4, check that the stage drives are centered;
- pump down the airlock, by pushing the end of the sample rod, straight, toward the column; while the red indicator light is on, the airlock is pumping.
- When the light goes out, rotate the holder clockwise, and allow the vacuum to pull in the holder, with your hand still on the handle.
- Turn the filament back to saturation
IX. Check the IMAGE WOBBLER setting
- Focus the image on the screen, look for minimum contrast.
- Turn on the IMAGE WOBBLER: the image on the screen should remain steady.
- If not, use the IMAGE WOBBLER A, B knobs.
X. Specimen Height Adjustment
- At 5Kx, focus a feature near the middle of the viewing screen.
- Either disengage the motor, or use the foot pedals to tilt the sample 15o , towards you.
- The feature should stay in the middle, if it doesn’t, use the z-adjust knob (located directly under the inserted sample holder) to bring it to center.
- Return to 0o , adjust the feature to center with the stage drives, and repeat the above two steps until the feature stays centered.
XI. Check the current center in the objective lens
- Focus the specimen at 20Kx.
- Center a feature on the screen.
- Turn the MED FOCUS knob six clicks to the left.
- If the feature has shifted off the center, return it with the ALIGNMENT: TILTS.
- Return to focus.
- If necessary, center the feature with the stage drives.
- Repeat the above procedure until the feature stays centered.
XII. Check the intermediate and projector lens alignment
- Center a large feature on the screen at 5K mag.
- Select SA DIFF and camera length 240, or the camera length to be used (60).
- Focus the center spot with the small, inner CAMERA LENGTH knob. The feature selected in MAG should be visible in the center spot.
- Switch between MAG and SA DIFF.
- Check that the feature remains centered in SA DIFF mode. If adjustment is necessary, ask for help. [Allen wrenches are needed on the intermediate lens (in MAG), located about eye level on the column, and the projector lens (in SA DIFF). Repeat until the feature remains centered in both modes.]
XIII. Voltage centering
- Increase the mag to 100K, and center a tiny feature or hole in the center of the screen.
- Turn on the HV WOBBLER.
- Adjust the ALIGNMENT: TILT knobs until the centered image moves radially, not in any direction.
XIV. Inserting the objective aperture
- Push SA DIFF.
- Rotate the appropriate objective aperture into the path of the beam.
- Focus on aperture with diff focus (the small, inner knob of the CAMERA LENGTH knob)
- Center the aperture around the beam.
- Push MAG.
XV. Astigmatism Correction
- At 100K, center a hole small enough to be seen through the binoculars.
- Overfocus the image, to view the dark Fresnel fringe inside the hole.
- If the line does not go around the hole symmetrically, adjust the OBJ STIGMATOR FINE knobs.
You’re done! Have a good session!
Session Shut Down:
- Turn off the filament emission.
- Step the HT down to 20, then shut off HT.
- Return spot size knob setting to 1.
- Remove objective and/or SAD apertures.
- Reduce magnification to 5 K
- Center the stage drives (also called specimen translators)
- Remove the sample from the specimen holder, and store the holder in the TEM, under vacuum.
- Log out in SUMS.
- Disconnect the CCD camera, turn off the cooler in the software, and turn off the power with the “ROOM LIGHTS” switch on the console.
Complete Shut Down:
- Turn the power key from ON to OFF.
- Wait 20 minutes for the automatic shut down procedure to complete.
Image a crystalline sample
Center a crystal, less than 1um in diameter.
Obtain a diffraction pattern of the crystal
Insert the appropriate size selected area (SA) aperture (encircles the crystal).
Push SA DIFF.
Remove the objective aperture.
Tilt the beam for darkfield
The pattern will shift on the screen; the transmitted spot will no longer be in the center.
Center the reflection (spot) of interest
Use the DARK field ALIGNMENT: TILT knobs to center the spot on the screen.
Obtain the darkfield image
Insert the smallest objective aperture around the spot in the center of the screen.
Remove the SA aperture.
Return to brightfield
It may be necessary to rotate to a larger objective aperture.