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78 WFS Series
an elliptical pupil by entering different values for X and Y diameter. Here, the mean
diameter defines the Zernike circle.
NOTE
This option 'Use Beam Width' must be switched off when entering Highspeed Mode
of WFS10 instruments because the beam width cannot be measured with a
sufficient accuracy in Highspeed Mode.
NOTE
The pupil diameter cannot be defined larger than the active camera area defined
with Camera Image Size in the Camera Settings . In this case the warning "Pupil
is larger than selected camera area" (see chapter Measurement Warnings and
Errors ) will occur. This limitation prevents Zernike calculations with increased
uncertainties because the measurement points (spots of the lenslets) are no more
equally distributed across the pupil area.
See chapter Minimal Beam and Pupil Diameter for the minimal pupil diameter
required for calculation of Zernike modes up to a desired order.
It is recommended to use a 'Circular Pupil' by selecting the appropriate option.
Here, only the diameter in X needs to be entered and the Y diameter is set to the
same value.
Pupil Center (mm)
The pupil center in mm can also be set manually or automatically.
It is recommended to enable 'Use Beam Centroid' in order to automatically adapt
the pupil center to the measured beam centroid coordinates. In case of fluctuations
of the beam position during the measurement, the Wavefront Sensor will
automatically follow the wandered spot. If you switch to manual input you can use the
' 0.0' button to set the pupil centroid to the center of the Wavefront Sensor.
NOTE
Manual definition of the pupil center requires a careful and stable beam adjustment,
otherwise the measurement results will suffer from increasing errors.
It is recommended to review the pupil size and position using the appropriate
functions in the 'Spot Field' and 'Beam View' displays. The 'Show Pupil' option
must be enabled in the appropriate configuration panels.
NOTE
This option 'Use Beam Centroid' must be switched off when entering Highspeed
Mode of WFS10 instruments because the beam centroid cannot be measured with
a sufficient accuracy in Highspeed Mode.
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