Transparent thin films of polyepoxypropylcarbazole polymer were produced using spin-coating technique. Optical materials constants such as refractive index of thin films and thickness were determined by optical spectroscopy. It was shown the possibility of variation of film thickness by polymer concentration in solution. It was shown that film thickness dependence on the concentration of solution is linear. Therefore this linear dependence can be used to predict the film thickness of spin-coated polymers if the solvent is known. The thickness can be varied from 170 nm up to 940 nm for the solution with concentration from 2.5% up to 12.5%. To confirm the validity of our method, we also carried out the interferometric thickness measurements and analysis with a thin film of polyepoxypropylcarbazole. The difference of obtained results of two methods averaged not more than 5%. The measured film thickness by transmission spectra of the polymer film was found to be well correlated to the results of interferometric thickness measurement. The refractive index of the polyepoxypropylcarbazole was 1.62, which was well above the refractive index of 1.49 for polymethylmethacrylate. It was found that the inclusion of even a small amount of a photosensitizer, such as CHI3, was effective in producing of high refractive index material with refractive index 1.64.