Vacuum thermal evaporation has, for some time now, been the principal method for the deposition of thin films, given, among other aspects, its simplicity, flexibility, and relatively low cost. Therefore, the development of models attempting to predict the deposition patterns of given thin film materials in different locations of a vacuum evaporation chamber are arguably important. With this in mind, we have designed one of such models for the thermal evaporation process of magnesium fluoride (MgF2), a common material used in optical thin films, originating from a tungsten boat source. For this we took several deposition samples in glass slide substrates at different locations in the vacuum chamber, considering as independent variables the mean deposition rate, and the axial and vertical distances of the source to the substrate. After a careful analysis by matrix method from the spectral transmittance data of the samples, while providing as output data the spectral transmittance, as well as the physical thickness of the films, both as functions of the aforementioned variables, the virtual surface of the source was determined.
In this work, it is shown a panoramically view of advances and works on fundamental optical technology developed and Physics
Section at Pontificia Universidad Católica del Perú PUCP in Lima Peru. This includes works in, precision optics manufacturing,
optical testing, and optical design and simulation and also in optical thin film evaporation and its design techniques
The present work studies the variation of refractive index of titanium dioxide thin films due to changes in the evaporation rate during the deposition process under high vacuum. The experiments were done by depositing thin films on a glass disk of 45 cm in diameter for different deposition rates. To characterize thin films the spectral transmittance in the visible range was measured at different points along of two perpendicular radii. The refractive index profile was then determined from these data by using an inverse synthesis method. The results permitted us to obtain the refractive index variation as a function of evaporation geometry for different deposition rates.
The present work studies the refraction index and physical thickness variation of deposited thin films over large glass substrates and source emission patterns variation, exclusively due to the type of material in the evaporation process at high vacuum. The employed method consists in varying the evaporated material and so obtaining the thin films physical thickness and refraction index in several points over the substrate through adjustment of the measured transmittance, comparing with the one obtained by simulation. The results show a radial distribution of the refraction index and physical thickness in dielectric thin films due to the material employed.