Polarized Sunglasses ?

I just purchased a really cool pair of CARRERA sunglasses on ebay.

They claim it has POLARIZED lenses.

Is there any "do it yourself" test for me to check whether or not the lenses are really POLARIZED?

Thanks.

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Look outside on a sunny day at things like the street, and car windshields.

It's easy, just tilt or "****" your head back and forth from one shoulder to the other, while wearing the sunglasses. Reflections in windows and glare from pavement will fade in and out from various surfaces.

Essentially, you're rotating the polarization plane of the lenses, and as it interferes with the polarization plane of light reflected at various angles, that light will dissapear.

You can even just stare at blue sky, it'll get darker and lighter as you tilt the lenses while looking through them.

Yea, if you tilt the lenses of the glasses at a certain angle, you will see a lot more light through them. I think their is a general normal tilting way you should tilt em' but some are different. When you tilt them the certain way, you are allowing the light to go through the polarized, "window blinds" like area, therefor it looks much brighter.

Cameron

Wear them into a store that sells Polarized glasses. Hold your glasses up to a known pair and rotate one pair 90 degrees to the other and try to look through them. If they are BOTH polarized, they will block out all light. If they do not block light, take two pair from the store and turn them 90 degrees to each other just to make sure.

Look at certain car's windscreen with and without your polarized sunglasses if you see a difference they are polarized. You can see some default on double glazing windows too !!! Enjoy it for fishing !!!

Most factory window tints are applied by dot, so if you look at a factory tinted window you will see little dots all over the place. That's how I can tell.

Just wear them while looking at an LCD display, (that's on of course)...and tilt your head, and then you can tell...apparently LCDs use polarized light 'cause as you tilt your head the LCD screen goes blank....

All of the above suggestions should work, but here is a really good one. Look at a Liquid Crystal Display such as a watch or calculator that has numbers on it. Rotate the item while looking at the display through your glasses. The screen should black out. LCDs are polarized. /ubbthreads/images/graemlins/cool.gif

Dang! Beaten by 30 seconds.

Did the LCD test and they ARE really polarized -- thanks!!!

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ACMarina said:
Most factory window tints are applied by dot, so if you look at a factory tinted window you will see little dots all over the place. That's how I can tell.

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Not sure about the "dot" explanation for factory tinted windows.

But "safety" or "toughened" glass (as usually used on modern cars—there is also laminated glass which is sometimes called "safety" glass too—but that is not what I am discussing here) will show patterns (generally irregular "dots") when viewed under polarized light (typically polarized light from a clear blue sky) and polarized lenses.

What you are seeing are the differential stresses in the glass caused by 1) heating the glass to near melting point then 2) passing the sheet glass over cool air jets that "freeze" the outside surface while letting the internal glass cool slower. This ends up placing the surface of the glass under compression and the interior under tension. These stresses will change the angle of transmission of polarized light (as well as making the surface of the glass more resistant to breakage from scratches).

-Bill

Learn something new every day!

What advantages do polarized lenses have in comparison to normal sunglasses.

Sorry, forgot to call the "safety glass" its US name of "Tempered Glass" (PS: and to finish the thought--it is called safety glass because if there is any scratch or chip that compromises the glass it will shatter into pieces no bigger than a handful of small gravel and not create large and dangerous shards)... If you look on any automotive and some glass in homes (typically sliding doors and windows extending near the floor) you should find "tempered" and the manufacturer's name etched into the glass.

Polarized glasses are useful because reflected light from glass surfaces and water (as well as from pavement and some other surfaces) can be polarized into one orientation. If you look at the object through a polarizing filter setup at 90 degrees to the reflected (polarized) light, the reflection will be blocked and you should be able to see what is under the surface (such as a fish) and you will have less eyestrain from glare from the road (and be able to see the lines easier).

-Bill

Yup test it with LCD screen at home. Or hold two polarized glasses, tilt and adjust them you should see nothing at some degree.

When I go to buy a pair of solarized sunglasses I wear a pair and tilt my head while looking at the rack and at times I can watch some of them go darker. I only buy polarized sunglasses because the extra glare blocking ability is nice and haze from hot roads (invisible puddles) dissappears. When I am golfing I sometimes look in the water and the polarized glasses allows me to see *free* golf balls which I grab with my 10 foot *scooper*. You can also wear an LCD watch when shopping as others have mentioned.

One thing.. watch out for LCD gas pumps you may have to tilt your head to read them at some angles using polarized glasses.

I find that some cheap sun-glasses are not properly polarized. I bought a pair from Costco and had a devil of a time with them. I finally realized (a year or so later) that I was seeing the polarizing effect differently in each eye. The lenses were maybe 20 or 30 degrees off between them. It gave me eye strain over the course of an hour.

To make sure they are sync'd hold them away from your face and look through both lenses at a polarized screen while rotating. Both should block about the same at about the same time. If one lags the other you may not be happy.

Daniel