Zeiss EVO - SE Detector

ZEISS 3 Product and Functional Description | 3.3 Detectors
3.3.3 SE Detector
Purpose
The SE detector is an Everhart-Thornley type detector. It detects SEs as well as BSEs.
Position
The SE detector is mounted on the wall of the specimen chamber, and is therefore classified as a
“chamber detector”. Due to its position in the chamber, the SE detector views the specimen later-
ally.
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1
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3
4
Fig.15: Schematics of the SE detector
1 Objective lens with through-the-lens
pumping
2 SE detector
3 Collector grid 4 Specimen
Function
Electrons moving to the detector are attracted/repelled by the collector grid and directed to the
scintillator. The electrons gain energy from the scintillator and thus are able to interact with a
phosphor layer, which generates photons (light). The light travels up a light pipe to a photomulti-
plier. The photomultiplier multiplies the flashes of light and outputs a signal that can be used for
imaging.
The collector voltage can be varied in the range between −250V and +400V.
A positive collector voltage generates an electrical field in front of the detector, thus directing the
low energy SEs towards the scintillator.
A negative collector voltage generates a field deflecting the low energy SEs so that they cannot
reach the scintillator and do not contribute to the signal. Only high-energy BSEs reach the scintil-
lator contributing to the image generation. This produces a pseudo-backscattered image, which
shows pronounced material contrast, but largely cancels surface properties and topography.
Fig.16: Comparison of SE detector images using positive and negative collector bias voltage: SE detector using
+300V collector bias: Good display of surface structures and topography (left), SE detector using –150 V collector
bias: Extremely strong topography, including shadow generation (right)
Instruction Manual ZEISS EVO | en-US | Rev. 10 | 354706-0780-006 33