THORLABS WFS20-14AR, Operation Manual

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Wavefront Sensor
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The smaller the image size, the fewer spots are used for calculation and thus, maximum
achievable Zernike order decreases. On the other hand, measurement speed increases.
The following image sizes are selectable, depending on the connected WFS instrument:
Camera Image Sizes - WFS20 Camera Image Sizes - WFS30 Camera Image Sizes - WFS40
The highlighted values are start-up defaults. The camera in the Wavefront Sensor instrument
determines the resolution (pixel density) and maximum available sensor area:
Item Sensor Size Max. Sensor Area
WFS20 1.5 MP 1440 x 1080 7.20 mm x 5.40 mm
WFS30 2.4 MP 1936 x 1216 11.34 mm x 7.13 mm
WFS40 4.2 MP 2048 x 2048 11.26 mm x 11.26 mm
In the case that the beam diameter is larger than the maximum sensor area, only the fraction of
the beam cross section incident on the active sensor area can be analyzed by the instrument.
When the input aperture is overfilled, the Wavefront Sensor can still provide correct results.
However, the pupil parameters must be selected carefully (see
Pupil Definitions Setup ).
The selectable image sizes for the Wavefront Sensor instruments can be found in the appropri-
ate Technical Data sections (see
Appendix ) as well.
The WFS20 instrument offers a binning mode ("bin2"). In this mode, four pixels in a 2x2 grid
are combined and averaged to yield one data point. The result is an increased frame rate with
the trade-off of reduced spatial wavefront resolution.
Similarly, the WFS30 and WFS 40 offer a "sub2" mode, in which subsampling selects a single
pixel out of a 2x2 grid to use for measurement. The measurement speed increases, with the
disadvantage of a lower spatial wavefront resolution and accuracy.
Note
Changing the camera resolution will also change the number of detectable spots. If the instru-
ment is operated with a User Calibrated
Wavefront Reference , a new User Calibration
may be required!
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