3,3’-Diethyloxadicarbocyanine iodide (DODCI)-dispersed polymer thin films were produced by hot-press of DODCI molecules densely dissolved in several polymers (poly(methyl methacrylate) (PMMA), poly(2-hydroxypropyl methacrylate) (PHPMA), etc.). A novel method for preparing a preform powder by coprecipitation in vacuo has successfully been developed and compared with a conventional coprecipitation method which uses good and poor solvents for polymers. Experimentally, an acetone solution of DODCI and polymer was directly injected into ultrahigh vacuum from the liquid phase through a modified needle valve. Deposits were formed on a heat-controlled substrate with rapid evaporation of a carrier solvent and they were hot-pressed to produce a transparent thin film. A new technique to control the allocation of dye associates in three-dimensional space and a new concept for optical elements have been proposed.