Zeiss Crossbeam 550, Instruction Manual

Page: 39 / 136

ZEISS 3 Product and Functional Description | 3.2 Main Components
3.2.4.3 InLens SE Detector
Purpose The InLens SE detector is a high-efficiency detector for high resolution SE imaging and detects
secondary electrons directly in the beam path. The detection efficiency of this detector results
from its geometric position in the beam path and from the combination with the electrostatic/
electromagnetic lens.
Position The annular shaped in-column detector is located above the objective lens.
1
2
3
4
Fig. 12: Schematics of the InLens SE detector
1 InLens SE detector
2 Beam path
3 Objective lens
4 Specimen
Operating
Principle
The primary electrons are accelerated by the acceleration voltage at the anode and, up to an ac-
celeration voltage of 20 kV, by an additional beam booster voltage of 8 kV at the liner tube. To
ensure that the electrons reach the specimen surface
4
with the energy set as acceleration
voltage, an opposing electrostatic field of the same magnitude as the beam booster voltage (8 kV)
is generated at the end of the objective lens by the electrostatic lens. This electrostatic field acts
as acceleration field for the SEs generated on the specimen surface.
At the InLens SE detector, the electrons hit a scintillator. This generates a flash of light that is led
out of the beam path and onto a photomultiplier by means of a lightguide. The photomultiplier
converts the light information into an electronic signal, which can be displayed on the monitor.
The efficiency of the InLens SE detector is mainly determined by the electric field of the electro-
static lens, which decreases exponentially with the distance.
Thus, the working distance (WD) is one of the most important factors affecting the signal-to-noise
ratio of the InLens SE detector.
As the tilt angle of the specimen surface affects the emission angle of the electrons, you should
avoid strong specimen tilting.
Info
The InLens SE detector can be used up to an acceleration voltage of 20 kV. At higher accelera-
tion voltages, the beam booster and thus the field of the electrostatic lens are switched off.
Without the field of the electrostatic lens, which attracts the secondary electrons, the effi-
ciency of the InLens SE detector is reduced.
Instruction Manual ZEISS Crossbeam 550L, Crossbeam 550 | en-US | Rev. 3 | 349500-8122-000 39