Mie theory and it's application in probe of cloud droplet

Mie theory of spherical particle is introduced in this paper. Using Mie theory, scattering energy distribution of typical-size cloud droplet is presented, as well as the relative intensity collected in certain solid angle of different size droplet. An airborne probe of cloud droplet is designed based on the Mie theory. In this probe, a 685nm diode laser is used to illuminate the cloud droplets in the sensitive volume. The scattering energy between 4 degrees and 12 degrees(solid angle) of forward scattering is collected. From the energy of the forward scattering, the sizes of the cloud droplets can be obtained. In the system, an aspheric lens system is used to provide uniform illumination with high use efficiency of laser. Most of the key parameters of the receiving optics system are presented, the designed deep of field (DOF) is 3mm. With this probe, the cloud droplet concentration of size between 4-50um can be measured.