Based on the design theory of film stack,H4 and SiO2 were selected as the high and low refractive index materials respectively. Through optimization by Macleod and TFCalc software, plus considering the internal electric field intensity distribution of film and laser induced damage threshold as well,the beam-splitting film with Tp=65±5% and Ts=30±5% in the 600-700 band in condition of 45 °± 3 ° incident angle has been achieved. Adopting electron beam ion assisted deposition system to development, the deposition parameters of materials has been optimized via orthogonal matrix experiment. The fabrication of thin film for laser polarization beam splitter has been succeeded. Its optical properties, mechanical properties and resistance to environmental test of the film have been approved to meet all using requirements.

Aiming at the special requirements for filter film of the optical prismatic system, basing on the design theory, and choosing the appreciate film materials, a high reflectance film and a splitter film are designed respectively. The films can satisfy with the optical requirement perfectly, when the incidence light is P polarized at the 25 angle in the range of the visible wavelengths (450nm~650nm). During the preparation process, the optical film absorption is solved by continually optimizing the process parameters, such as temperature, rate of evaporation and ion assisted deposition parameters, etc. Meanwhile, the error produced in the process of preparation is analyzed and revised through several repeated tests and researches, so that the control precision of layer thickness is improved. Finally the high-reflective film with average reflectance over 99.5% in the 450~500nm band and the beam splitting film with transmittance and reflectance ratio of 1:1 and 1:2 are prepared respectively (both errors are below 1%) in the 450~650nm band. After the spectrum testing and analyzing, the spectrum curve shows that all the parameters meet the basic requirements for usage.