You can find a LCD (Liquid Crystal Display), let the glasses level at the screen, at this time, the lens has not any change. Then put the glasses clockwise rotation up to 45Â°angle, if you see the color of the lens becomes deeper, and when you turn back, it become normal, this is polarized sunglasses. If you turn it, there has no change, and then this is not polarized sunglasses. But you should note that it must be a liquid crystal display.
Polarized lenses can reduce glare and the intensity of ultraviolet light, and polarizing sunglasses can completely cut off glare caused by scattering, reflection. But it can not completely cut off those harmful lights. To know whether sunglasses are polarized, you can do like this. Generally speaking, there may be an obvious polarization lens material static on the sunglasses. What's more, using polarization test piece is a good choice to know whether sunglasses are polarized, the pattern on the polarization test piece can not been identified with naked eyes, while you can see clearly through polarizing lens. According to the LCD display principle, we can also identify whether your sunglasses are polarized. When you observe the LCD screen of your cell phone through polarizing sunglasses, you can see the blank screen when you are rotating the cell phone.
There should be a test card for polarized sunglasses you can buy from most optical stores. You can't see the image on the card unless with your polarized sunglasses. Or you can hold them up to a computer screen with the front of the lens facing the screen. When you rotate the lenses around, you are expected to find the lights reflected on the screen are alternated with darkness if the lens is polarized.
If you're shopping for sunglasses and aren't sure if they're polarized, you can easily check by holding two identical pairs at 90 degree angles to each other. As you turn one pair slowly to 90 degrees, your vision through the second lens should get visibly darker. If the lenses aren't actually polarized, you shouldn't notice a change.You could also do this trick with most LCD smartphone screens. Just look at your phone in portrait orientation, then slowly turn it to landscape to see if you notice any change. If you can though, try to test this with a pair of glasses that you know are polarized beforehand, since not every phone screen behaves the same way.
"You just need to look at your phone in portrait orientation, then slowly turn it to landscape to see if you notice any change. If you can though, try to test this with a pair of glasses that you know are polarized beforehand, since not every phone screen behaves the same way." Sr: Internet gmail sign in