SPECS 2D-CCD, User Manual

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Manual V2.docx | Status 10.12.2015 | Version 1.0
A.4.2 Alignment of spin deflector 2 with a phosphorous screen
With the vacuum system vented, remove the Ferrum detector part from the
CCD/deflector/rotator part. Mount the small phosphorous screen on the end of the deflector
lens system. Mount the CF 200 flange with a CF 40 window instead of the Ferrum detector.
This flange with window is included in the delivery.
When the system has been pumped down, set the electron gun at the optimum position on
the sample, as described in section A.3.1. It requires a very high electron current to see an
image on the phosphorous screen.
Set Lens mode LAD, so that the electrons are deflected by 90°. Use E
kin
20 eV, E
p
= 160 eV and
set RotL to +1. Set the aperture wheel to Slit5/open.
Use SDefl2X and SDefl2Y to center the beam on the screen at the exit of the 90° deflector.
The beam will not be round; it will have a symmetric half moon shape, as shown in Figure 48.
Figure 48. The image on the alignment phosphorous screen.
Adjust all four deflection voltages SDefl1X, SDefl1Y, SDefl2X and SDefl2Y carefully until you
have maximum symmetry in the spot and at the same time have the spot in the center of the
screen. Also check that RotL can be changed from +1 to -1 and back, without significant
changes to the image.
The beam now passes correctly through the lens system of the deflector/ rotator. Note down
all deflection settings for further use.
Vent the system and remove the phosphorous screen and install the Ferrum detector
instead.