Development of a Polarimeter Equipment for Sunglasses According to the Brazilian Standard NBR15111

摘要

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.