Abstract: A liquid particle, which often appears in the laser holograghic measure-merit, can be treated as a semi-transparent spherical one. The sphere affects the incident by the refraction, diffraction, reflection, absorption and attenuation of impurity. At first, the particle is considered as a highly aberrated spherical lens, so that its focal length is gained, and then the equivalent thin lens is found under the condition of the equal focal length and equal light distance. By considering the refractive and diffractive effects of the particle in terms of the thin lens, the coinples amplitude transparency of the transparent particle can bo derived. The reflective, absorptive and attenuative effects of the semi-transparent particle can be revised in the complex ampliude transparency by a synthetical transparency.

Key words: semi-transparent, particle, particle model, lens, complex amplitude transpa rency