In order to eliminate the polarization effect caused by oblique incidence of light, a design method of depolarizing prism based on Brewster condition is introduced. Select three common thin film materials, aluminum oxide and magnesium fluoride, to achieve the same effective refractive index of P-polarization, and achieve the same reflectivity of the two polarization states at a specific wavelength, which can achieve the effect of depolarization. Improving the distribution of the film layer has achieved the optimization of the reflectivity in a specific wavelength domain. The angular characteristics of a depolarized beam splitter prism using birefringence characteristics have been studied. Three design schemes have been provided with 30%, 50%, and 70% reflections. The polarization separation caused by an incident angle deviation of 2 ° is less than 5%.
