Circular polarizing filter CW vs CCW?

BugEZ · Post by **BugEZ** » Thu May 01, 2014 3:36 am

Can polarizing filters for cameras be obtained that distinguish light circular polarization in clockwise and counter clockwise orientations? Apparently the lenses in 3D glasses used at 3D movies do this, however I do not see any rotation labeled on the inexpensive circular polarizing filters available at my local camera store.

Thanks!

Keith

TheLostVertex · Post by **TheLostVertex** » Fri May 02, 2014 10:36 am

I wouldnt be surprised if they were all manufactured to have the same handedness. Edmund sells various films though, which you can selecte your desired orientation. http://www.edmundoptics.com/optics/pola ... ?#products

Ancient1 · Post by **Ancient1** » Fri May 02, 2014 10:39 am

Could it be as simple as which side you look through?

rjlittlefield · Post by **rjlittlefield** » Fri May 02, 2014 11:13 am

Ancient1 wrote:Could it be as simple as which side you look through?

I'm not following this. When I look through the wrong side of a circular polarizer, it's just a linear polarizer. What am I missing?

--Rik

Ancient1 · Post by **Ancient1** » Fri May 02, 2014 11:29 am

Sorry Rik, it was intended to be tongue in cheek... I probably should have added a confused smiley after it.

BugEZ · Post by **BugEZ** » Fri May 02, 2014 4:59 pm

Many thanks Eugene, Steven and Rik.

My first stop will be the multi-plex cinema down the street to beg some used 3D glasses. Failing that to Edmunds, or perhaps I will order a pair of inexpensive 3D clip-on glasses from the web...

Keith

rjlittlefield · Post by **rjlittlefield** » Fri May 02, 2014 6:32 pm

Ancient1 wrote:Sorry Rik, it was intended to be tongue in cheek... I probably should have added a confused smiley after it.

Ah yes, the perils of text. But I'm afraid a confused smiley wouldn't have helped much either. Then I likely would have just thought you really were confused, instead of me!

--Rik

Chris S. · Post by **Chris S.** » Fri May 02, 2014 6:54 pm

Keith,

You might check out American Polarizers, Inc. (I have no experience with them). Their Website lists some interesting offerings, including circular polarizers in both left and right-handed versions. Not too expensive--a glass-mounted 25mm one is $25, for example.

They also offer linear polarizing film and quarter-wave retardation film, if you want to make your own circular polarizers, which case you could set them up with the handedness you need.

This MIT video is a nice demonstration of using a quarter wave retarder to change linear polarization into circular polarization. The important bits start about three minutes in, though the setup before that is useful for clarity.

(Question for folks who've worked with quarter wave retarders: Is my intuition correct that, if a quarter wave plate is placed in front of a linear polarizer such that light becomes circularly polarized in a left-hand fashion, this circular polarization will switch to right-handed if the quarter wave plate is rotated 90 degrees around the optical axis?)

Cheers,

--Chris

BugEZ · Post by **BugEZ** » Fri May 02, 2014 8:24 pm

Chris S. suggests

You might check out American Polarizers, Inc. (I have no experience with them). Their Website lists some interesting offerings, including circular polarizers in both left and right-handed versions. Not too expensive--a glass-mounted 25mm one is $25, for example.

Thanks Chris! I looked over there website. A good idea, especially if I strike out at the theater. They also sell clip-on 3D glasses with left and right circular polarizing lenses.

I am doing some experiments with light transmitted through and reflected off of fly wings.

Keith