Fabrication of filter film using in polarized light guide prism system*

摘要

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.