Study On The Apparent Optical Properties Of Spherical Particles In Liquid Absorbing Medium

The interaction between light and particles has always been a research hot topic.Scattering,transmission,reflection and other optical phenomena will be produced in the interaction.All of these phenomena are closely related with the particles' own properties,such as the particle size,etc.The Mie scattering theory provides the theoretical basis for studying the interaction between the sphere and the electromagnetic wave.Many scholars have studied the efficient algorithm and developed the corresponding computer program to come to the single scattering characteristics of spherical particles accurately.In the traditional Mie formula,the medium containing spherical particles is assumed to be a non-absorbent medium.However,medium is regarded as absorbent in many cases,so it is needed to correct the traditional Mie scattering law on this premise.In the engineering applications of light scattering,scattering intensity in the far field must be calculated accurately,but in the condition of the absorbent medium,there exist differences between the scattering intensity calculated in classic Mie scattering law and the actual measurement,so it is necessary to study the apparent optical properties of particles in the absorbent medium.Currently,study on the apparent optical properties in the west is at the theoretical analysis stage,so the application of apparent optical properties to the measurement of particle size and other engineering fields,and solving scientific problems in engineering application are a significant study direction of apparent optical properties.This paper traced back to the apparent optical parametric equation of particles in the absorbing medium,chose the simulated milk-fat as the research object,and deeply studied its apparent optical properties,obtaining the optical parameters of the fat particles in the two solvent and quantifying the differences between the apparent optical parameters and the Mie optical parameters.The internal relationship between the apparent scattering phenomenon and the imaginary part of the refractive index of the medium is also studied and the critical value of the imaginary part of the refractive index in the engineering application of the apparent optical properties is determined.The application of the apparent optical properties in the engineering application is realized by analyzing the particle size.The main research contents include:1.Tracing back to the apparent optical parametric equation of particles in the liquid absorbing medium,the paper chose the simulated milk-fat as the research object,and made the simulation and contrastive analysis on the apparent optical properties and Mie scattering properties of fat particles in the two solvent of ethyl acetate and ethyl alcohol,quantifying the difference between the apparent scattering coefficient and Mie scattering coefficient of the simulated milk-fat.The calculation results show that in the condition of the same wavelength and the same medium,the difference is small,which indicates that the changing rules of the apparent scattering properties and Mie scattering properties can be comparable.The internal relationship between the imaginary part of the refractive index of the medium and the apparent optical phenomena is also studied,and the critical value of the imaginary part of the refractive index of medium in the engineering application is worked out.If it is less than the critical value,the apparent optical phenomena can be neglected and the Mie optical parametric can be used.2.The analytic equation of particle size has been worked out based on the apparent optical parameters.Firstly,the paper analyzed the theoretical foundation of measuring the particle size with the method of light scattering,in which the calculation of optical parameters is based on the classical Mie scattering equations.As for the absorbing medium,the Mie optical parameters are replaced with the apparent optical parameters,which is a theoretical supplement to the method,thus to improve the accuracy of inversion equation.Secondly,the analytic equation of particle size is deducted based on the apparent optical parameters and the simulation study on the result of the equation is made through the self-designed simulation system.Lastly,excited by different wavelength,the particle size curves based on the Mie optical parameters and the apparent optical parameters are drawn and analyzed.The analysis results show that there exist differences on the particle size based on the apparent optical parameters and the Mie optical parameters,the former is smaller.3.The influential factors on measuring the particle size in the liquid medium are studied.Firstly,a light experiment system is built,including the light source,sample pools,the selection of optoelectronic components and the design of the transport system with constant temperature.Secondly,the simulated milk-fat is prepared and dissolved with two kinds of absorbing medium of ethyl acetate and ethyl alcohol.Homogeneous pre-processing is made to make the particle size well distributed,determining the optimum simulation solution concentration.Lastly,with the self-designed optical experiment system as a platform,the receiving angle of the scattered light,the excited wavelength of the simulation,the optimal measurement temperature and other factors are determined.4.The experimental verification of the apparent optical properties and the analytic equations of particle size in the absorbing medium are conducted.Firstly,the apparent optical properties of spherical particles in the absorbing medium are verified,and the results show that the scattering intensity calculated on the apparent optical properties is closer to the actual value.Secondly,the correctness of the particle size analytic equation based on the apparent optical parameters is verified and the results show that in contrast with the actual value,the particle size difference obtained from the equation is less than that obtained from the Mie optical parameters,To illustrate,the apparent scattering influence measurement of particle size,and proved by experiments,measurement of particle size based on the apparent scattering particle size the has higher accuracy,has engineering application value.