For many practical applications such as combustion, environmental control, fluid mechanics, and chemical reaction, we need to measure the properties of particles such as size and refractive index-temperature ratio quickly and precisely. As a approximation method of a rigorous light scattering theory, geometrical-optics approximation (GOA) is used widely because of high speed calculation and simple procedure structure. The GOA method is suitable for light scattering by large particles. For particles w...