lentil.zernike_fit

lentil.zernike_fit(opd, mask, modes, normalize=True, rho=None, theta=None)[source]

Fit a Zernike basis set to an OPD.

Parameters
  • opd (array_like) – OPD to fit.

  • mask (array_like) – Mask defining the extent to compute the Zernike polynomial over. All nonzero entries are included in the result.

  • modes (array_like) – List of modes (Noll ordering) to fit.

  • normalize (bool, optional) – If True (default), the output is normalized according to [1]. If False, the output value ranges [-1, 1] over the mask.

  • rho (array_like, optional) – Radial coordinates of the mask array. rho should be 0 at the origin and 1 at the edge of the circle.

  • theta (array_like, optional) – Angular coordinates of the mask array in radians.

Returns

List of coefficients fit to the supplied OPD over the specified number of Zernike modes.

Return type

ndarray

Example

>>> import numpy as np
>>> import lentil
>>> mask = lentil.circlemask((256,256),128)
>>> coeffs = np.random.rand(4)*100e-9
>>> opd = lentil.zernike_compose(mask, coeffs)
>>> fit_coeffs = lentil.zernike_fit(opd, mask, np.arange(2,4))
>>> print('Tip/tilt coefficients:', coeffs[1:3])
>>> print('Fit tip/tilt coefficients:', fit_coeffs)

Tip/tilt coefficients: [9.69097470e-08 9.94332699e-08]
Fit tip/tilt coefficients: [9.69545890e-08 9.94781119e-08]

See also

zernike_remove()

References

[1] Noll, RJ. Zernike polynomials and atmospheric turbulence. J Opt Soc Am 66, 207-211 (1976).