3.4 Adjusting the Electron Optical System
3 - 20
(c) Auto Beam Setting (ABS)
ABS combines the automation functions of AFS (Auto Filament Saturation), ABA (Auto
Beam Alignment), ABCC (Auto Brightness Contrast), and AFC (Auto Focus Control) to
produce good-quality SEM images. This feature can be helpful when steps such as
the setting the filament current and the adjusting the gun alignment axes after a filament
is replaced. For details, see the individual Auto functions. After the ABS function is
activated, the Auto Gun Bias function is set to the checkmarked conditions.
See the following sections:
3.4.2.2 Axis Alignment Items in Detail
3.3.2 Setting the Accelerating Voltage and a Filament Current
3.5.4 Image Brightness and Contrast Adjustment
3.5.5 Focus and Astigmatism Correction
(d) Setting the Probe current
Click the ↓
button to select the desired probe current level from 0 to 100, from a
displayed list. The lower the probe current setting, the higher the resolution that can be
obtained. For observing low-contrast specimens and performing X-ray analyses, the
Probe Current level should be set high to produce a large amount of probe current.
The default is 50.
Small adjustments can be made by using the Up/Down
buttons to change the probe
current in 0.1 increments. A numerical value can be entered directly from the keyboard
(use the Return key to set).
(e) Setting a WD (Working Distance)
Working Distance (WD) refers to the distance between the bottom of the objective lens
and the surface of the specimen. The scale on the Z-axis of the specimen stage
corresponds to the Working Distance.
Fig. 3.4-3 Definition of WD
Specimen
WD
Objective
lens
