THORLABS WFS20-14AR, Operation Manual

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Wavefront Sensor
Zernike Fit Tab
Fit up to Zernike Order
Use this control to define the highest order of Zernike polynomials that
should be used to fit the measured wavefront within the pupil area.
According to the well known set of Zernike polynomials, ( r
n
), the highest ra-
dial order, n, determines the number of Zernike modes that contain n or
lower potencies of the pupil radius
r .
By default, the highest Zernike order is set to n = 4 which implies a total
number of 15 Zernike modes. The resulting coefficients are displayed as a
bar graph chart on the Zernike Coefficients panel.
The higher the Zernike order, the more Zernike modes are used to recon-
struct the measured wavefront shape. The best wavefront reconstruction is obtained using the
highest Zernike order 10 utilizing a total number of 66 Zernike modes.
Auto
If 'Auto' is enabled, the Zernike order is set to the highest possible value that is feasible. The
highest number of Zernike modes must not exceed the amount of detected spots within the pu-
pil.
Highest Order in Fourier and Optometric Calculations
This control specifies that Zernike terms up to the selected number of 2,
4, 6 be used to calculate the numerical calculation of the Fourier coeffi-
cients M, J0 and J45 as well as the Optometric parameters Sphere,
Cylinder and Axis.
Mode Selection for Wavefront Reconstruction
This table provides a list of all calculated Zernike coefficients listed in rows. The total number of
rows is determined by the '
Fit up to Zernike Order' control.
The check box at the left side determines whether this mode should be used for a wavefront re-
construction or not. For instance, to see the reconstructed wavefront without primitive modes
piston, tip and tilt (which often dominate the 3D graphic) use the following setting: