5 OPERATION
EM210F-1
5-15
5.2.5 Aperture
Insertion
5.2.5a Condenser
aperture
This aperture restricts the illumination area on the specimen and illumination angle. The
larger the aperture size, the larger the illumination angle. The image brightness becomes
brighter when a bigger aperture is used.
1.
Obtain the MAG mode.
2.
Converge the electron beam as much as possible with the BRIGHTNESS
knob (L1-
⑥
).
3.
Center the beam with the SHIFT knobs (L1-
⑧
, R1-
③
).
4.
Select the largest aperture.
?
Manipulate knob 2 and 3 to find the aperture on the fluorescent screen if
aperture does not appear on the screen.
5.
Select the aperture size to be used with knob 1.
Knob 2
Knob 3
Knob 1
Fig. 5.13 Aperture knobs
6.
Adjust the aperture position using the aperture shift knobs so that the
electron beam converges and diverges concentrically when the
BRIGHTNESS knob (L1-
⑨
) is turned slowly clockwise and counterclockwise.
b. Correctly aligned
a. Incorrectly aligned
Fig. 5.14 Aperture adjustment