Re: Polarized sun glasses

Nate Nagel wrote:

Okay I'm officially confused. I always read about how great
polarized glasses are for riding and driving. And back in my
driving days, I had a set of polarized ray-bans that would stay
in the car.

Now I decided to upgrade my Rudy Project cycling sunglasses. I
bit the bullet, and paid far too much money for a pair of their
polarized lenses. The lenses just arrived, and they have a "not
suitable for driving or road use" warning sticker on them.
Anyone have any idea why?

I wrote to them asking this same question, but while I wait for
their official response, I wanted to see if anyone else had this
problem.

Polarized lenses help over water, fishing etc.

I'm sold on them for driving, haven't tried them riding yet. I
have a set of green-tinted polarized prescription Ray-Bans and I
love them to pieces. The one drawback I've found is that they
produce very strange interference patterns when looking out
through car windows with aftermarket tint film, but none of my
personal vehicles are so equipped so this is a non-issue for me.

Try looking at old VW or other tempered glass windshields. The
stress in such glass causes all angles of polarization and these
interfere with sight with Polaroid glasses. Also, the stress
patterns are strikingly visible with such glasses.

I don't know if tempered glass has ever been acceptable for
windshields here in the US, at least for vehicle years likely to be
found still on the road. My '49 Chevy had laminated glass as well
as my '55 Studebaker, and while I actually know of another '49 Chevy
nearby with regular license plates on it no less, that's probably
getting close to the upper limit for age of a vehicle as viable
transportation. In fact, back when those cars were built, laminated
glass was required on *all* windows, and it was only later that
tempered glass was allowed for side and rear windows. AFAIK,
laminated ("safety") glass is still required on windshields.

It wasn't at the time when VW used tempered glass for windshields and
other windows. The reason I mention the windshield is that tempered
glass crazes into corn kernel sized particles that I'm sure may riders
have seen scattered along roads. However, if the window doesn't fall
out, it remains as a rough "bathroom window" through which one cannot
identify objects. For this reason a clear, untempered circular area
in front of the diver was annealed to remain transparent in the event
of a pebble crazing the window while driving at speed.

http://en.wikipedia.org/wiki/Tempered_glass
http://www.dropgates.com/y2y/glasslogos.html
http://en.sevenload.com/photos/VbJFKjt-Glas-Securit

These windows have circular stress rings that can be seen with
polarized light or with Polaroid glasses. The window is not polarized
in any orientation and its polarization is invisible to the human eye.
Polaroid glasses would not be useful for driving an old VW (pre 1960)

--
Jobst Brandt
.

Relevant Pages

  • Re: Polarized sun glasses
    ... polarized glasses are for riding and driving. ... Try looking at old VW or other tempered glass windshields. ... in such glass causes all angles of polarization and these interfere ...
    (rec.bicycles.tech)
  • Re: Polarized sun glasses
    ... polarized glasses are for riding and driving. ... My '49 Chevy had laminated glass as well as my '55 Studebaker, and while I actually know of another '49 Chevy nearby with regular license plates on it no less, that's probably getting close to the upper limit for age of a vehicle as viable transportation. ... In fact, back when those cars were built, laminated glass was required on *all* windows, and it was only later that tempered glass was allowed for side and rear windows. ... human eyes don't detect polarizing. ...
    (rec.bicycles.tech)
  • Polarization in 3D glasses
    ... It seems that the polarization depends on the ... After the movie I got pleasantly surprised that the glasses ... one lens looks transparent in the ... the second pair at 90-degrees (as if the person is still ...
    (sci.optics)
  • Re: Polarization in 3D glasses
    ... circular polarization with a quarter ... wave film is used. ... and the other lens turns it a more blue hue. ... Turn the glasses round, to point the wrong way, and look through the ...
    (sci.optics)
  • Re: Polarized Instrument Display
    ... the polarization is in the cover glass for the LCD. ... never use polarized sun glasses, ... You either have defective polarization on your glasses or the LX has ... you should be able to see the LCD screens ...
    (rec.aviation.soaring)