Influence of the size distribution of particles on the MCF through fog-filled medium

Based on the theory of Mie and pulse wave propagation in discrete random medium, using the size distribution spectrum of fog particles, the characteristics of laser pulse propagating in fog is studied under various visibility conditions. The fog particles distribution changing with the visibility is obtained, and for larger visibility, fog particles are moving towards smaller size. These results show that the distribution of the size of fog particles is influenced by the visibility. With the visibility increasing, the radiation fog droplet number density is increased slowly. The relationship of the two-frequency mutual coherence function (MCF) with the difference frequency is obtained. The amplitude and phase of MCF are compared with that considering about the average fog number density. When the visibility is about 2Km, the obtained MCF is similar to that when the average fog concentration is 10⁷/m³. With the visibility increasing, the phase of the MCF changes tremendously. When the transmission distance is 5Km, considering the gamma distribution of droplet size spectrum, the normalized value of the MCF changes in relationships with the difference frequency. The coherence bandwidth is close to that of the droplet number density of 10⁷/m³ while the visibility is 2Km. When the visibility is 3Km, the coherence bandwidth is several times for that while the visibility is 1Km.