  The efficient optical tool for elimination of the phase and amplitude
distortions produced by imperfectness of the optical elements in microscope
lightpath considered. This robust procedure described by simple theoretical
model proved to be successful to repair the noisy images with noise to signal
ratio close to 100. It is shown that Van Cittert - Zernike theorem provides
adequate description of imperfect microscope operating under both coherent and
incoherent illumination conditions and having turbid media in object and
intermediate planes.
