Characterization of a Viable Particle by Optical Prorerties

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A method to recognize the compositions of moving airborne particles are discussed in this study. The method is based on optics, and refractive indices of paticles were utilized to recognize their compositions. Numerical analisis were performed, and experiments on actual particles (PSL) were made.In numerical analisis, the probability to determine the refractive index and the size of a homogenous spherical particle by measuring scattering intensities at some two scattering angles is evaluated. Now, bacteria, water and PSL partilces were interested, so Objective particles have the size parameter range from 2.0 to 6.0, refractive index range from 1.3 to 1.7. Higher probability of determining them was obtained with the conbination of foward and side angle than that with other conbinations.The insturument (C.A.P.system) to measure the scattering intensities of the actual moving single particle at arbitrary two scattering angles was made. With C.A.P.system, the intensities scattered by PSL particles were measured. The influence on the detected intensity, that was yielded by the relation of the intensity distribution at the cross section of LASER beam and the parh of a moving PSL particle, was evaluated. The obtained intensty curve had a shape like Gaussian curve, it was caused by using LASER that was Gaussian beam for light source, and its peak value and width were determined by the path of particle. So the shapes were utilized to know the parh of particle.Furethermore, the refractive indicies of PSL particles were calculated with relative scattered intensities at each detected angle to intensity at 30^<○> in the case that particulate diameters were Known.