THORLABS WFS Series, Operation Manual, Page: 84 / 157

© 2007-2012 Thorlabs GmbH
81 Operating Instruction
Wavefront Reference
The Thorlabs WFS series Wavefront Sensors are factory calibrated and provide an
internal reference for the measured spotfield centroids. This internal reference is
based on the well known and highly accurate parameters
pixel distance of the CCD sensor = 4.65 µm (WFS)
pixel distance of the CMOS sensor = 9.9 µm (WFS10)
lenslet pitch of the microlens array = 150 or 300 µm, respectively
calibrated out-of-center shifts in for a plane wavefront under vertical incidence
negligible torsion between CCD chip end lenslet array
correction parameters for lenslet astigmatism
This means, the centroid positions for all spots created by the lenslet array are
accurately known for a plane wavefront at vertical incidence and acts as an '
Internal
reference '.
It is recommended to use this internal reference unless a perfect plane or spherical
wavefront is available to perform a User Calibration. There is no default user
calibration delivered with t he instrument. Therefore, as soon as the '
User
Calibrated Reference ' is activated, you will be informed that such a default
reference is created and saved to the application directory.
This default user reference file is identical to the internal reference.
Perform a
User Calibration using a plane or spherical wavefront to fill the default
file with reference data measured by the user.
In order to be distinctively the user reference file name is automatically composed
of the
WFS serial number
MLA name
Camera resolution index
for instance WFS_M00224955_MLA150M-5C_2.ref. The file itself is stored into the
application directory.
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