On 1/28/07 11:50 PM, in article
1170057000.658437.227290@s48g2000cws.googlegroups.com, "Bucky"
<uw_badgers@email.com> wrote:

High quality expensive polarized glasses do not give you significant
improvement over any non-distorting polarized glasses. I get mine from the
99¢ store when I can.

These glasses work best when light reflects off a surface at the Brewster
angle. The Brewster angle is related to the index of refraction of the
reflecting/scattering surface. Yes, black asphalt does indeed have a
refractive index. Technically, absorbing surfaces have what is called a
complex refractive index. At the Brewster angle, only light with its
electrical field parallel to the surface gets reflected and that is almost
totally removed by the polarizer. Away from the Brewster angle, some
vertically oriented light will get through.

As the sun rises and falls from dawn to dusk, the angle of reflection
changes. Depending on the time of the year and time of the day, you may
actually get reflection at the Brewster angle.

I found such glasses very useful for fly fishing. At times, it make small
flies highly visible against the glare reflected off of the water. Toward
dawn or dusk, the glare suppression is greatly reduced and getting the extra
light by not using the polarizing glasses often gave better seeing even with
the glare.

On my Toyota, the polarization state of the odometer was exactly
incorrectly. It would cost no more to do it correctly for new models.

The spots you see arise from the stress in the windshield. Light gets
partially polarized when scattered in the atmosphere. The blue sky,
scattered by aerosols and air molecules is partially polarized. This
scattered light's polarization state gets modified going through the
stressed glass and adhesive. As a consequence light is absorbed in the
polarizer as a function of windshield stress.

Actually, I find polarized glasses useful for driving into glare, but the
cannot be relied upon to give good performance all the time. You may notice
mirages that look like water in the road at dips. Polarized glasses help get
rid of that.

Bill
-- Fermez le Bush--about two years to go.

I bought a quality pair of polarized sunglasses (Hobie, $60 sale/$160
retail) for driving purposes, especially to help in daylight rainy
conditions. I read about the theory of polarized light, and thought it
would be a great improvement over regular sunglasses. However, I've a
been quite disappointed in their performance.

Whenever I came across a situation that I thought should make a
difference (like sun reflecting off a wet road, or drizzling
conditions), I compared the polarized sunglasses vs a non-polarized $5
sunglasses. I honestly couldn't notice any difference in glare
reduction.

On the other hand, polarized lenses had some negative effects. LCD
displays (radio, odometer) have a disconcerting shimmer (because my L
and R eyes see different brightness due to their different angles).
When I looking at other cars' windshields, I see a disconcerting
effect of a grid of spots (possibly due to safety glass?) And I can
barely see a rainbow! =)

What are other people's experiences with polarized sunglasses? They'd
probably be really great if you're at the beach or on the water, but
for land and driving use, I think I'll get non-polarized next time.

http://www.hobiepolarized.com/eyewear.aspx