Time to learn about some magic folks, but first! A story.
So! Knowing me and my love of sleep, most of my friends are surprised when I tell them my favorite job was a research position that involved waking up at 4:30 am. But it was really the best: I got to stomp all over the prairie and wrangle critters (for science!) and everything. I only stumbled over a rattlesnake once. It did require some special equipment on my part, however. Namely cacti-resistant boots, cargo pants (tip: if you’re doing field work, get a pants with pockets big enough to hold a Nalgene. It’s worth it and you’ll thank me later) and sunglasses. I couldn’t get just any sunglasses, though. I was working outside for up to 11 hours, that is a LOT of sun exposure and my eye sight is bad enough without throwing sun damage into the mix. The solution for me was polarized sunglasses (also a hat).
If you’ve lived in a place with any significant amount of sun, you’ve probably seen polarized sunglasses at the store. If you grew up in a place that’s as damp, grey and dark as if it were being swallowed by a giant oyster, you probably haven’t. Or you didn’t until you moved to a place with sun and got a job that had you working outside all day (COUGH COUGH). To understand polarized lenses, you need to understand light.
Light has electric fields that move in waves and these waves acan be oriented in all different directions. Light from a lamp or the sun is like this and thus is unpolarized light. Reflective surfaces can polarize light so that it all travels in one orientation: horizontally. Besides being damn bright and annoying, this light can damage your vision. To combat this, you can get polarized lenses. Polarized lenses have a coating of polymers all aligned parallel to one another. This coating only allows light to pass through that has an electric field perpendicular to the orientation of the polymers.
Scary diagram, but I want you all to see the important bits the official way, first. Namely, the orientation of the wave (the transmission axis of energy) and the direction it flows in.
Simplified diagram
You would think that the light would need to be oriented parallel to the polymers, but such light waves actually get absorbed by the polymers. Anyway, the result is that half of unpolarized light is blocked, while polarized light from glare is virtually eliminated.
Eye saving MAGIC.
Although polarized lenses are expensive, they are very much worth it for protecting your sight if you spend a lot of time in the sun.
Oh, FACT: lots of companies can say they sell polarized lenses even if they don’t. To tell for sure, find a highly reflective surface or a monitor screen and tilt your head to the side. Looking at it normally, it won’t be very bright, but after you tilt your head all the way to the side, the surface should be almost black.
Sources
–. 2012. “Polarization of Light.” Physics. Whitman College. Walla Walla, WA. Lecture.
Tyson, Jeff. “How Sunglasses Work” 14 July 2000. HowStuffWorks.com. <http://science.howstuffworks.com/innovation/everyday-innovations/sunglass.htm> 02 April 2015.
Image Credits
Prof Josh (seriously cannot remember his name, someone HELP) for 1st.
Heartland Optical for 2nd.
CTS Wholesale Sunglasses for 3rd.
Daily Science (blog) 