THORLABS WFS150, Operation Manual

Page: 73 / 123

71 Operating Instruction
© <2007> ... Thorlabs GmbH
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.
Note: The pupil diameter can be defined larger than the active camera area
defined with Camera Image Size in the Camera Settings . So, a wavefront
measurement is enabled also in case of the beam to be analyzed is wider than
the sensor area. Please, take into account that such a calculation may suffer from
increased uncertainties because the measurement points (spots of the lenslets)
are no more equally distributed across the pupil area but are concentrated at the
center.
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 '
à
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.
Limit to Pupil Interior
Enabling this option will limit the wavefront calculation and display of it to the pupil
interior. Points outside the pupil, that do not go into the Zernike calculation
anyway, will not be recognized for statistical wavefront analyses.
The 3D wavefront display on the Wavefront Panel will show only the wavefront
data within the pupil when this option is enabled.
Note: In case the 'Measured Wavefront' is selected for display, this option
influences the total measured wavefront distortions (PV, RMS). Distortions only
within the defined pupil area are usually lower that the total measured distortions
outside the pupil.