Filtering light reflected from water or wet floors, polarized lens protects eyes from discomfort and fatigue. It has been gained wide popularity nowadays. However, normally few know how to distinguish polarized lens from ordinary one. It is hoped that the following can serve as a help.
At first, a specific test piece has been created to distinguish polarized lenses. There is certain drawing hided in the text piece which can not be observed with naked eyes. Only with polarized lenses can those drawing be seen, for polarized lenses make light radiating from the drawing shine into eyes in one direction.
Next please find a liquid crystal display, whether of a computer or a cell phone, and to put the polarized lens that you want to test parallel to the display. By this time no change shows on the polarized lens. Then, to turn the polarized lens clockwise to an angle of 45 degree, and you will notice that the lens darkens. While turned again, the lens will return to normal. If those so called polarized lens appear to unchanged no matter how to turn them, they turn to be counterfeiting.
Last but not the least, among so many ways to distinguish polarized lens, the simplest one is to overlay one polarized lens with another vertically. For the special design of polarized lenses which merely allow collimated light to penetrate, when two qualified lens overlay, most of the light are cut out. That is to say two lapped qualified polarized lenses are lightproof.