  The statistically independent Karhunen-Loeve modes of refractive indices with
isotropic Kolmogorov spectrum of the covariance are calculated in a sphere of
given radius, rendered as series of 3D Zernike functions. Many of the symmetry
arguments of the associated 2D problem for the circular input pupil remain
valid. The technique of efficient diagonalization of the eigenvalue problem in
wavenumber space is founded on the Fourier representation of the 3D Zernike
basis.
