The polarization filter is used to change the balance of light. The polarization mirror can selectively let the light vibrate in a certain direction through. In color and black and white photography, it is often used to eliminate or reduce the strong reflection on non-metallic surfaces, improve the color saturation of the picture, and obtain higher quality images and colors. Gray in appearance, it allows about 80 percent of linearly polarized light to pass through and less than 1 percent of linearly polarized light that vibrates perpendicular to its polarization. Polarizing mirror, also known as polarizing mirror, abbreviated as PL mirror, is a kind of color filter. Polarization mirror is divided into linear polarization mirror (LPL mirror, ordinary polarization mirror) and circular polarization mirror (CPL mirror, circular polarization mirror).