About polarized sunglasses

If you want to see your Harley-Davidson in rainbow colors, very easy, just put on some polarized sunglasses.

I was quite surprised when I drove for the first time with my new shades. Took some time before I got them, as I need prescription glasses, and as I used my old sunglasses mainly for driving car and bike, the optician recommended polarized glasses.

Polarization can be observed through scattering when the light passes via the atmosphere. This scattered light creates the color and brightness in a clear sky. Once this scattered light is subjected to partial polarization, it can increase the contrast in such a way that darkening of the sky in a photograph is possible. During sunset, this effect is easily observed from the horizon angling 90 degrees from the setting sun. The brightness of the clouds and sky are drastically reduced. This is the reason why polarization filters are utilized in sunglasses.

But while driving on my MP3 scooter back from work, wearing the new sunglasses for the first time, a very strange effect could be observed: if I look at or through the windshield, it shines in rainbow colors.

After several attempts I managed to capture it on photo. Excuse the somewhat blurred second shot, I had to hold my sunglasses in front of the camera, and refocus, as I use prescription glasses.

Here another view, each time you change your angle of view, the rainbow shifts

But I must say I see better with polarizes sunglasses, the view is much more sharp, full of contrast, without flares and reflections. The rainbow colors mainly appear on the plastic windshields, very strong with my Piaggio MP3, much less pronounced on the Road King Classic. Also very different is the view at the rear window of a car. The glass seems dotted with fingerprints, and as soon as I take the polarized glasses off, the fingerprints disappear. But then I am not able to look through the glass anymore, as its reflections are strong it seems like a mirror.

I think its definitively better (and safer) with the polarized glasses, even with the rainbows on some plastic surfaces.

I read that some car drivers have problems looking out of their car when they added tinted film to their windows, and I see nothing on my Apple iMac when wearing the polarized glasses, the screen turns completely black. This made me worry I would not be able to watch the directions on my Satellite navigation unit, a Garmin ZUMO 660, but after a quick test I can report: the SatNav display is not disturbed by any rainbow or black screen.

The explanation for the dots on rear car windows is not simple: its tempered glass, it has been manufactured in a vertical tempering oven containing small surface depressions resembling dimples along one edge. These marks are caused by the pointed metal tongs which support the glass during its passage through the oven. Glass which is passed horizontally through an oven may contain a very slight surface wave caused by contact with the rollers. The waviness can sometimes be detected when viewing reflected images from a large distance. Finally, the air quench nozzles discharge air in a fixed, reciprocating or rotating motion, and the area of air quench can be seen through polarized glass as arrays of iridescent spots or lines… Understood? Well, I did not write that but ….

I do not want to miss my polarized sunglasses, although there is some getting used to.

Do you see rainbows?


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