Experimental Measurements Of Optical Constants At Normal Temperature Of Translucent Organic Polymer Materials

Most organic polymer materials have the characteristics of chemical stability,good processability,low density and low cost,and are widely used in aerospace,optical lens,electronics industry,radiation cooling and other fields.However,the current data on the optical constants of organic polymer materials is extremely scarce,which limits its application in the field of thermal radiation.The optical constants of ten commonly used organic polymer materials at normal temperature were measured,which can solve the heat radiation problems of these materials more conveniently,and has great value in engineering application and theoretical research.In this paper,the optical constants in the 0.4-2 μm band of six materials such as polydimethylsiloxane(PDMS),poly(methylmethacrylate)(PMMA),polycarbonate(PC),polystyrene(PS),polyethylene terephthalate-1,4-cylclohexylene dimethylene terephthalate(PETG)and ploymethylpentene(TPX)are measured by the ellipsometry method combined with the ray tracing method.The optical constants of the five materials of PMMA,polyvinyl chloride(PVC),polyetherimide(PEI),polyethylene terephthalate(PET)and PCTG in the 0.4-2μm are measured by the double optical pathlength transmission method.The optical constants of these ten materials at 2-20 μm are measured by ellipsometry.The measuring instruments are V-VASE and IR-VASE spectral ellipsometers.The measured samples were smooth and the surface was clean and free of oxide layers.The optical constant of PMMA measured by ellipsometry combined with ray tracing method in the 0.4-2 μm band is consistent with the optical constant measured by the double-path transmission method.The optical constants of PDMS measured by ellipsometry in the 2-20 μm band are consistent with the data in the literature,indicating that the optical constants measured in this paper are very accurate.The measured refractive index n of all organic polymer materials decreases gradually with increasing wavelength in the 0.4-2 μm band,and satisfying the Sellmeier dispersion relation.In the infrared band,molecules selectively absorb infrared rays of a specific wavelength to generate energy level transitions,thereby generating absorption peaks.The measured organic polymer material has an absorption peak near 1.7 μm,the reason is that the first-order doubling stretchingvibration of the C-H bond in the methyl group and the methylene group in the organic polymer causes,and the absorption peaks at the remaining wavelengths can be combined with the respective molecular formulas to determinethe vibration type of the chemical bond.Obtaining the optical constants of these organic polymer materials,the radiation property parameters of these materials can be accurately calculated,thereby providing data support for numerical simulation of spectral characteristics and increasing the accuracy of radiation heat transfer calculation.