  We probe turbulence structure from centimetric to metric scales by
simultaneous imagery at mid-infrared and visible wavelengths at the VLT
telescope and show that it departs significantly from the commonly used
Kolmogorov model. The data can be fitted by the von Karman model with an outer
scale of the order of 30 m and we see clear signs of the phase structure
function saturation across the 8-m VLT aperture. The image quality improves in
the infrared faster than the standard lambda^{-1/5} scaling and may be
diffraction-limited at 30-m apertures even without adaptive optics at
wavelengths longer than 8 micron.
