Optical thin films exhibit inevitable polarization effects at oblique incidence, which leads to the spectral splitting of s-and p-polarization components. Generally, s-polarized light initially enters Philips prism, and then the light is modulated to p-polarized light by liquid crystal light valves if they are in "on state". Consequently, minimum splitting of s-and p-polarization components is required to gain optimum efficiency and improve contrast of the system. The novel design method is based on a broad-band F-P thin film interference in which both sides of transmittance band can be used for long-wave-pass or short-wave-pass filters, and through suitable refinement it is possible to achieve zero separation between two polarization components.