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ZEISS
3 Product and Functional Description | 3.3 Optional Components and Accessories
3.3.1.5 aSTEM Detector
Purpose
The optional aSTEM (annular Scanning Transmission Electron Microscopy) detector consists of an
electron detector underneath an ultrathin specimen.
The aSTEM unit is equipped with diodes that are switched on or off in order to allow dark field
and bright field imaging.
1
2
3
1
Incident electron beam (primary electrons)
2
Thin specimen
3
Info
Risk of malfunction: The diode segments are sensitive to the light that is used for illumination
in TV mode (infrared and white).
When you use a diode detector, always make sure that the TV illumination is switched off. If
the CCD Mode is set to Auto Detect, then the TV illumination is automatically switched off
when a diode detector is used.
Operating
Principle
The aSTEM detector is a pneumatically retractable multi-mode detector with a 12-stub specimen
holder for bright-field and dark-field detection.
The diodes of the aSTEM detector collect transmitted electrons below the ultrathin specimen.
A special arrangement of the diodes allows a parallel detection of bright field (BF), oriented dark
field (ODF), annular dark field (ADF), and high angle annular dark field (HAADF). There are one
bright field segment (S1), two dark field segments (S2 and S3), one annular dark field segment
(S4), and one high angle annular dark field segment (S5).
Two different models are available:
§
The aSTEM4 allows detection of four channels in parallel.
§
The aSTEM1 only collects one signal at a time.
Instruction Manual ZEISS Crossbeam 350 | en-US | Rev. 3 | 349500-8111-000
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