The use of polarizing filters in sunglasses has become increasingly common worldwide. Although the Brazilian standard NBR15111 has specific requirements for its use (position and efficiency), there is not a proper machine to make the specified measures. This paper describes the development of an equipment according to NBR15111. A study was made using a 120,000 lx white LED light source, and an analyzer, which is an assembly of two polarizing filters with its polarization axis orthogonally aligned, both in front a light sensor with 16 bit resolution. The proposed system was able to measure the polarization efficiency of all the sunglasses categories, including the critical situation of the category 4, 3% of light transmittance, and efficiency of 8:1. The direction of the polarization plane is determined with the resolution of 0.056°in this critical situation. The results meet the standard requirements of 0.5° for angle measures and 8:1 for filters efficiency, which shown that the proposed equipment is able to check the quality of the polarizing filters used in sunglasses, that are commercialized in the Brazilian market.
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