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ZEISS
3 Product and Functional Description | 3.2 Main Components
Fig. 36: Charge compensation by adjusting chamber pressure and collector bias. Left: Reducing the collector bias
from 82 % to 78 % results in the elimination of banding effects at 40 Pa. Right: Reducing the pressure in the speci-
men chamber from 40 Pa to 20 Pa results in the elimination of banding effects at a collector bias of 79 %.
Parameter
Description
Acceleration voltage
3 kV to 30 kV
Possible application range for VPSE G4 detector. However, sufficient
contrast can be obtained only at higher voltages.
3 kV to 7 kV
Low voltage application with VPSE G4 detector.
7 kV to 25 kV
Standard application for VPSE G4 detector.
Working distance
6 mm to 8 mm
For low voltage applications (3 kV to 7 kV)
8 mm to 15 mm
For standard applications (7 kV to 25 kV)
Aperture
30 μm
The standard aperture is recommended for many applications.
7.0 μm to 20 μm
With these apertures, the probe current is frequently too low to ob-
tain a sufficient signal-to-noise ratio and the required contrast.
60 μm
Higher probe currents frequently improve the contrast.
120 μm
Only recommended for analytical applications.
Specimen tilt
Avoid large angles of tilt, if possible. Slight tilting can improve effi-
ciency.
Operation mode
The VPSE G4 detector is used mainly in the VP mode.
As the VPSE G4 detector detects light, it can be used as a simple
cathodoluminescence (CL) detector in high-vacuum mode.
Instruction Manual ZEISS SIGMA series | en-US | Rev. 7 | 352102-9344-006
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