Generic TEM Operating Procedures

Operating Instructions

for a TEM  

Italic print indicates an optional "advanced" alignment procedure which should be carried out at least once each week  

1.         Switch on the High Voltage

2.         Switch to the desired kV, allowing the emission meter to settle.

3.         Increase the filament control to within half a division of the old setting or until a reading shows on the meter or no further than 1/3 to 1/2 a turn

4.         Reduce the magnification and adjust the condenser control (BRIGHTNESS) to obtain a bright spot

5.         Adjust the condenser to form the smallest spot when the image is magnified to be 2 to 3cms across

6.         Reduce the filament heating until the image breaks up.

7.         Increase the filament heating to obtain a spot and halo

8.         Balance the spot and halo with the gun alignment tilt controls - Right Hand door

{9.        Check the "gun alignment shift" centre at spot size 2 with the condenser adjusted to form the smallest spot

10.       Check the "illumination alignment shift" at spot size 3 with the condenser adjusted to form the smallest spot

11.       Repeat 9 and 10 for a constant centre}

12.       On spot size 2 with the condenser adjusted to form the smallest spot, saturate, and centre the spot with the illumination alignment shift, spread the condenser clockwise.  Use the bias control to obtain saturation 10-15uA above the current indicated when the filament is switched off.

13.       Align the condenser aperture with its alignment controls

14.       Re check 12 and 13 for a constant centre

{15.      De saturate slightly, focus the filament image with the condenser control and then with the two condenser stigmator.}

16.       Re saturate but leave a very slight dark mark on the image

17.       Insert a specimen

{18.      Check for specimen movement when tilting and compensate

            a)         Centre a feature on the screen with the stage controls ~ 5,000X

            b)         Release the tilt clamp and tilt to 10degs

            c)         Bring the selected feature back to the field centre with the Z' control on the tilt mechanism.  (Knob under the specimen rod)

            d)         Take the tilt back to zero and re centre the feature with the stage drives

            e)         Repeat b), c), d) until the centre is constant.}

19.       Turn to a low mag, spread the condenser (CLOCKWISE) and find a suitable area of specimen.

20.       Turn a knob to or select DIFFRACTION or SA DIFFRACTION and trim to a bright spot with the DIFFRCTION LENS control and the condenser control

21.       Insert and centre the objective aperture (specimen level one click per aperture).

22.       Turn to the main MAGNIFICATION control and adjust magnification, focus and illumination to the desired levels.  Remember to focus the binocular on the screen using the pointer as your guide.

{23.      If the image moves at focus: rock the focus control and adjust for minimum movement with the "illumination alignment tilt" controls}

24.       To take a photograph -

            a.         Have the screen flat.  Set the illumination for a suggested exposure time 3 - 4 secs

            b.         Press FILM ADVANCE

            c.         Focus & Correct the astigmatism at the highest magnification

            d.         Drop to the photo magnification and re focus - check thet the specimen is NOT DRIFTING.

            e.         Lift the screen to expose and then advance the film.

            f.          Record the data