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11. Insert the liner tube into the liner pipe. Mount the anode by turning it clockwise, and
replace the electron gun to its original position. This concludes the condenser lens aperture
replacement process.
Figure 5.3-11 Replacing the Condenser lens Aperture (4)
5.4 Objective Aperture Replacement
The objective aperture is built into the liner tube. After the system has been in use for about
6 months and it appears that there is image deterioration (an out-of-focus condition), replace
the objective aperture. When replacing the objective aperture, it is recommended that the
condenser lens aperture be also replaced at the same time.
1. Introduce air into the specimen chamber.
Close the application program, and press the [EVAC/AIR] button to introduce air into the
specimen chamber.
2. When the blue LED lights up as shown in Figure 5.2-1, it is an indication that the
evacuation is complete; turn off the power switch.
CAUTION : If the system was in use until immediately before the cover was opened,
the Wehnelt and the anode around the filament could still be hot. To
avoid burns from touching it, perform filament replacement work by
allowing a minimum of 30 minutes after the power switch was turned off.
3. Wait for a minimum of 30 minutes, and then open the top cover. Holding onto the lower
part of the top cover with your finger tips, gently lift it.
4. There is a rubber cushion on the left side of the electron gun. Tilt the electron gun to the
left side of the system until it touches the cushion, and then gradually open the electron gun,
as shown in Figure 5.3-1.
Liner Pipe
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