1.The light transmittance of Polarizer is 41.5%, dullness is 99.8%. 2.Polarizer is more than 30%, dullness is 99.9%. Above the surface should not have hemp, scratch, the ragged edges, and should not have the degum, the attraction, the impurity, the steam bubble between it. The incident light, the compound light, or the monochromatic light turns the linearly polarized light by the polarizing filter, then causes the light complete extinction after the polarizing filter. The commonly used polarizing filter may use in the polarized light quantitative assay, the light measured mechanics, the glass manufacture, the attraction analysis, gem appraisal for automobile, photographic camera and so on, its use is widespread ,and it is an important optical element in the optical instrument application of polarized light.