1. When buying a polarizer in a regular glasses shop, there will be a test piece with some pictures inside. You can't see it without wearing a polarizer. You can see it when you put it on. In fact, this test piece is specially made, using polarized light. The principle allows the polarizer to see the parallel light from the inside picture, so that you can see the picture hidden inside, not the perspective, which can be used to detect whether it is a true polarizer.
2, polarizer has a feature, that is, the lens is extremely light, very thin, in the time of resolution, you can take other ordinary sunglasses to compare the weight texture.
3. When you buy, two polarized lenses are stacked vertically, and the lens will appear opaque. The reason is that the polarizer lens is specially designed to allow only parallel light to pass through the lens, and most of the light is blocked when the two lenses are stacked vertically. If there is opacity, it turns out to be a polarizer.
4, the lens and the LCD screen, you can choose the calculator display, color screen mobile phone display, computer LCD display, etc., placed in parallel. Turn the polarizer. Looking through the polarizer to look at the LCD screen, you will notice that the LCD screen will flicker and dim as the polarizer rotates. Experimental principle: The different colors of the liquid crystal screen are the polarization principle of the liquid crystal molecules used. If it doesn't change anyway, it's not a polarizer.