  We study the intensity spatial correlation function of optical speckle
patterns above a disordered dielectric medium in the multiple scattering
regime. The intensity distributions are recorded by scanning near-field optical
microscopy (SNOM) with sub-wavelength spatial resolution at variable distances
from the surface in a range which spans continuously from the near-field
(distance $ \ll \lambda $) to the far-field regime (distance $\gg \lambda $).
The non-universal behavior at sub-wavelength distances reveals the connection
between the near-field speckle pattern and the internal structure of the
medium.
