5 OPERATION
EM210F-1
5-33
d
B: when astigmatism exists
a: when astigmatism does not exist
Fig. 5.32 Astigmatism in the objective lens
5.3.6b At High Magnifications
An amorphous specimen (the specimen supporting film itself or specimen itself) is used
for astigmatism correction at high magnifications.
1.
Select “Maintenance” on the “TEN Controller” main menu to display the
“Alignment Panel for Maintenance” screen.
2.
Set the magnification to 100,000 times or higher in the MAG mode.
3.
Obtain suitable image brightness using BRIGHTNESS (L1-
⑦
) and SHIFT
(L1-
⑧
, R1-
④
).
4.
Manipulate OBJ FOCUS (R1-
⑦
) to focus the image.
5.
Use the trackball (SC-
②
) or X,Y buttons (SC-
①
) to obtain an amorphous
specimen on the screen using the .
6.
Depress OBJ STIG (L1-
⑤
) or select “DEF select-OL” on the “Alignment
Panel for Maintenance” screen.
7.
Slowly turn OBJ FOCUS back and forth from the in-focus position to observe
a phase image.
8.
Manipulate DEF/STIG (L1-
⑩
, R1-
④
) so as to make the phase image as
separated tiny spots (Fig. 5.33a shown below).
a: Hole image when
astigmatism does not exist
b: Hole image when
astigmatism exists
Fig. 5.33 Effect of objective astigmatism
