3.4.4 Focus 1 and Focus 2
The two focus parameters set the voltage applied to Focus 1 and Focus 2 lens elements, as well as the lens currents.
The voltages are related to the Energy parameter in the same way as the Extractor parameter—"Extractor" on page 14
for further details. As with the Extractor parameter, the display shows the current voltage of the selected focus para-
meter; however, it shows a percentage in Modify mode.
Figure 8: Viewing the Focus 1 parameter
Please note the following conditions when setting the focus parameters:
■
Observe the comments given in the source manual concerning the different beam modes (broad beam FWHM
~800
μ
m means F2=0, fine beam mode ~120
μ
m F1=F2~77 %).
■
You can set the focus electrodes in the range 0…99.99 %.
Danger—High Voltages Present!
Do not disconnect any cables without turning off the mains supply switch of the PU IQE 12/38. Wait at
least 30 seconds after switching off before disconnecting to avoid risk of serious injury or death!
To set the energy:
1. Press the Focus1 or Focus2 button, depending which you want to set. The corresponding menu is displayed.
Figure 9: Setting the focus parameters.
2. Press the Modify button. The LED above the Modify button will light and flashing triangles will appear below the
parameter value. The voltage value of the focus will change to a percentage value (relative to the Energy).
3. Enter a new value using one of the following methods:
■
Turn the jog shuttle until you reach the desired value.
■
Press and hold Num while entering the desired number using the numerical keys. The numbers are entered
from right to left.
4. Press Modify to accept the value. If you want to change the value, press Modify again to enter the edit mode.
3.4.5 Emission
The Emission menu allows the control of the filament via the emission current during operation.
16
April 26, 2013
PU IQE 12/383.0
Chapter 3 Front Panel Control
