We study both theoretically and experimentally the transmission of coherent light by a drop pattern (dew). The theory is based on the Kirchhoff scalar approach to diffraction. The polarization of the diffracted wave in the zero diffraction order is analyzed separately. The intensity in the zero diffrac-tion order in the far zone is an oscillatory function of the drop size. These oscillations are observed with a pattern of water drops growing on glass. The model allows the evolution of the important parameters of the drop pattern (average radius and surface coverage) to be obtained from the light intensity in the zero diffraction order.