The diffraction of a laser beam with a spatial amplitude-phase modulation in the form of regular interference pattern behind random phase object as biological tissue model is studied. The interference effects of speckle-fields formed in diffraction zone are considered. The concept of interference of mutually shifted partially developed identical speckle fields has been employed. The evolution of visibility of average intensity fringes formed in scattered field has been studied for the objects with different statistical parameters modeling various cell structures including objects with an oscillating correlation coefficient of phase inhomogeneities. The behavior of the speckle field interference induced by the focused spatially-modulated laser beam diffraction on the random phase objects has been studied. A new measuring technique of statistical parameters of transparent or reflecting random phase objects is discussed. The technique is based on the usage of the probing beam with regular interference pattern, focused on a moving object, and on measurement of contrast of average intensity fringes, formed in scattered dynamic specklemodulated field. Biomedical applications of the developed modeling and measuring techniques are discussed.

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The diffraction of a laser beam with spatial amplitude-phase modulation in the form of regular interference pattern behind random phase object is studied. The interference effects of correlation of speckle-fields formed in zone of diffraction are considered. To physically interpret the observed effects, there has been employed the concept of interference of mutually shifted partially developed identical speckle fields. The evolution of visibility of average intensity fringes formed in scattered field has been studied for the objects with different statistical parameters including objects with an oscillating correlation coefficient of phase inhomogeneities. The correlation properties of formed partially developed speckle fields are considered for an illuminating Gaussian beam with account of the observed interference effects.It has been shown that under certain conditions the form ofvariation ofthe fringe visibility coincides with the form of the correlation coefficient ofthe complex amplitude of the boundaiy field (the field in the plane, located in the inarnediate vicinity to the object plane) and, hence, is uniquely defined by inhomogeneities parameters of the object by standard deviation, correlation radius and correlation coefficient form. The application possibilities ofthe considered processes for diagnostics ofphase scattering objects complying with the model ofa random phase screen are discussed.