uneven polarized sunglasses

Hi folks,

I recently purchased a new pair of perscription sunglasses with
polarized lenses. (They weren't cheap ones, ether...) The
polarization on the lenses seem very uneven to me. If I look at a
clear blue sky, I can see that the lenses looks splotchy, as if the
direction of the polarization was not uniform throughout them. I see
this as well if I examine them with a polarized camera filter.

I've had polarized glasses before, and I've not noticed this, although
it's not something I explicitly looked for. This pair seems
particularly distracting - I've actually had these redone by the lab,
with similar results both times.

Before I take these back again, I'd like to know if I'm expecting too
much. More specifically:
- In general, how even should the polarization on perscription
sunglasses be?
- How much should a strongish perscription (~-5) affect the evenness of
the polarization?
- Would the fact that these are high IOR lenses affect how even a
result I can expect?

Thanks for any insight,
-p

 

Thanks for the response - it's very helpful. I'm aware of the effects
you mention (stress patterns on glass, etc.) and this is entirely
different. I guess they're going back again. Bleh.

Thanks again.

-p

 

None.[/QUOTE]

Not none with me!

Looking at any kind of glare via reflection shows it --
especially via tilting the head back and forth (left-right) --
HUGE and OBVIOUS difference.

Something in physics about non-porarized light, when
reflected, or maybe glancing reflection, gets polarized
at right angles to the plane of something -- was LONG ago,
that course.

And that effect is the *reason* for buying polarized
glasses, for reduced glare reflected from highway when
driving eg into setting sun.

Ditto for piercing sky-reflection when looking at angle
into eg a fishing-stream -- can see fish, bottom, etc
much clearer.

At least that's my experience -- although maybe not everyone's.

Cheers!

David